An-Najah Staff

Optimization of hybrid photovoltaic/wind system for Kuala Terengganu, Malaysia has been implemented by considering optimal sizing of photovoltaic array, wind turbine, and battery. The optimization technique is done based on loss of load probability and system cost. Simulation models of hybrid photovoltaic/wind system are developed by using daily solar energy and wind speed records and considering many configurations of photovoltaic array, wind turbine, and storage battery. The optimization performed in this research aims to select the optimal capacities of photovoltaic array and wind turbine, which give minimum system cost.

This article presents a method for optimizing the tilt angle of photovoltaic module/array installed in the five sites in Malaysia. The optimization method is based on the Liu and Jordan model for solar energy incident on a tilt surface considering monthly and seasonal tilt angles. The optimization results showed that a seasonal optimum tilt angle change is recommended for the peninsular Malaysia, while a monthly optimum tilt angle change is recommended for east Malaysia comprising the states of Sabah and Sarawak. By applying the monthly optimum tilt angle, the collected yields by the PV module/array in Kuala Lumpur, Johor Bharu, Ipoh, Kuching, and Alor Setar increased by 5.03, 5.02, 5.65, 7.96, and 6.13%, respectively. On the other hand, applying the seasonal optimum tilt angle for the same regions increased the collected yields by 4.54, 4.58, 5.70, 4.11, and 5.85%, respectively.

This paper presents models for global and diffuse solar energy on a horizontal surface for main five sites in Malaysia. The global solar energy is modeled using linear, nonlinear, fuzzy logic, and artificial neural network (ANN) models, while the diffuse solar energy is modeled using linear, nonlinear, and ANN models. Three statistical values are used to evaluate the developed solar energy models, namely, the mean absolute percentage error, MAPE; root mean square error, RMSE; and mean bias error, MBE. The results showed that the ANN models are superior compared with the other models in which the MAPE in calculating the global solar energy in Malaysia by the ANN model is 5.38%, while the MAPE for the linear, nonlinear, and fuzzy logic models are 8.13%, 6.93%, and 6.71%, respectively. The results for the diffuse solar energy showed that the MAPE of the ANN model is 1.53%, while the MAPE of the linear and nonlinear models are 4.35% and 3.74%, respectively. The accurate ANN models can therefore be used to predict solar energy in Malaysia and nearby regions.

This paper presents a new method for predicting hourly ambient temperature series for Malaysia using generalized regression neural network, GRNN. MATLAB was used to develop the GRNN using the weather records for Malaysia. The developed model has five inputs and one output. The inputs of the proposed model are hour, day, month, sun shine ratio and relative humidity, meanwhile ambient temperature is the output. To evaluate the accuracy of the GRNN, three statistical parameters, namely, the mean absolute percentage error, MAPE, mean bias error, MBE, and root mean square error, RMSE are considered. The GRNN results give an accurate prediction of ambient temperatures for the selected for testing months with average values of MAPE, MBE and RMSE of 2.65%, 4.05% and 0.347%, respectively. The advantage of the proposed method is that it is able to predict ambient temperature at sites where there is no ambient temperature measuring instrument installed.

Background: Toxicology in Malaysia has experienced rapid development and made great progress in education and research in conjunction with economic development in Malaysia over the past two decades.
Objectives: The main objectives of this study were to analyse the research originating from Malaysia and published in toxicology journals and to examine the authorship pattern and the citations retrieved from the Scopus database.
Methods: Data from 1 January 2003 till 31 December 2012 were searched for documents with specific words in the toxicology field as a ‘source title’ and Malaysia as an affiliation country. Research productivity was evaluated based on a methodology we developed and used in other bibliometric studies by analysing: (a) total and trends of contributions in toxicology fields between 2003 and 2012; (b) Malaysian authorship pattern and productivity; (c) collaboration patterns; (d) journals in which Malaysian researchers publish; (e) the classification of journals to Institute for Scientific Information (ISI) or non-ISI; (f) impact factors (IFs) of all publications; and (g) citations received by the publications.
Results: In total, 290 documents were retrieved from 55 international peer-reviewed toxicology journals. The quantity of publication increased by around 10-fold from 2003 to 2012. The h-index of the retrieved documents was 20. Of the 55 journal titles, 42 (76.4%) have their IF listed in the journal citation reports 2012. Forty-two documents (14.5%) were published in journals that had no official IF. The total number of citations, at the time of manuscript writing (5 August 2013), was 1707, with a median (interquartile range) of 3 (0–7). Malaysia collaborated mostly with countries in the Asia-Pacific regions (18.3%), especially India and Japan, followed by the Middle East and Africa (10.0%), especially Palestine and Yemen.
Conclusion: The present data show a promising rise and a good start for toxicology research activity in Malaysia. The sharing of relevant research questions by developed and developing countries can lead to research opportunities in the field of toxicology.

Summary What is known and Objective:  Drug–drug interactions (DDIs) cause considerable morbidity and mortality worldwide and may lead to hospital admission. Sophisticated computerized drug information and monitoring systems, more recently established in many of the emerging economies, including Malaysia, are capturing useful information on prescribing. Our aim is to report on an investigation of potentially serious DDIs, using a university primary care–based system capturing prescription records from its primary care services. Methods:  We retrospectively collected data from two academic years over 20 months from computerized databases at the Universiti Sains Malaysia (USM) from users of the USM primary care services. Results and Discussion:  Three hundred and eighty-six DDI events were observed in a cohort of 208 exposed patients from a total of 23 733 patients, representing a 2-year period prevalence of 876·4 per 100 000 patients. Of the 208 exposed patients, 138 (66·3%) were exposed to one DDI event, 29 (13·9%) to two DDI events, 15 (7·2%) to three DDI events, 6 (2·9%) to four DDI events and 20 (9·6%) to more than five DDI events. Overall, an increasing mean number of episodes of DDIs was noted among exposed patients within the age category ≥70 years (P = 0·01), an increasing trend in the number of medications prescribed (P < 0·001) and an increasing trend in the number of long-term therapeutic groups (P < 0·001). What is new and Conclusion:  We describe the prevalence of clinically important DDIs in an emerging economy setting and identify the more common potentially serious DDIs. In line with the observations in developed economies, a higher number of episodes of DDIs were seen in patients aged ≥70 years and with more medications prescribed. The easiest method to reduce the frequency of DDIs is to reduce the number of medications prescribed. Therapeutic alternatives should be selected cautiously.

In this research, an optimisation for building integrated hybrid PV/diesel generator system for zero load rejection for Malaysia is performed. The optimisation is performed considering a loss-of-load probability (LLP) less than 0.01. However, the daily averages of solar energy for Malaysia and a mathematical model of a hybrid PV/diesel generator system are used in this optimisation. The optimisation presented in this paper aims to calculate the optimum capacities of a PV array and diesel generator, which investigate the minimum system cost. An optimisation problem in terms of system units’ cost is solved graphically in this study. Moreover, the optimised system is compared to other energy source choices to highlight its feasibility. The recommended configuration of a PV/diesel system located in Malaysia is CA = 1.2, CDG = 0.3, while the optimum CB is 0.1. The results of the optimisation show that a PV/diesel generator choice is more feasible compared to a standalone PV system or diesel generator system because it reduces the system cost by 35%.

This paper presents an iterative method for optimizing inverter size in photovoltaic (PV) system for five sites in Malaysia. The sizing ratio which is the ratio of PV rated power to inverter’s rated power is optimized at different load levels using different commercial inverters models. Hourly solar radiation and ambient temperature records are used to develop a Matlab model for a PV array and inverter. The model aims to estimate the inverter’s efficiency in terms of PV array output power and inverter rated power. The results showed that the optimum sizing ratios for Kuala Lumpur, Johor Bharu, Ipoh, Kuching and Alor Setar are 1.21, 1.43, 1.31, 1.37 and 1.26, respectively.

What is known and Objective: Drug–drug interactions (DDIs) cause considerable morbidity and mortality worldwide and may lead to hospital admission. Sophisticated computerized drug information and monitoring systems, more recently established in many of the emerging economies, including Malaysia, are capturing useful information on prescribing. Our aim is to report on an investigation of potentially serious DDIs, using a university primary care–based system capturing prescription records from its primary care services.  Methods: We retrospectively collected data from two academic years over 20 months from computerized databases at the Universiti Sains Malaysia (USM) from users of the USM primary care services.  Results and Discussion: Three hundred and eighty-six DDI events were observed in a cohort of 208 exposed patients from a total of 23 733 patients, representing a 2-year period prevalence of 876·4 per 100 000 patients. Of the 208 exposed patients, 138 (66·3%) were exposed to one DDI event, 29 (13·9%) to two DDI events, 15 (7·2%) to three DDI events, 6 (2·9%) to four DDI events and 20 (9·6%) to more than five DDI events. Overall, an increasing mean number of episodes of DDIs was noted among exposed patients within the age category ≥70 years (P = 0·01), an increasing trend in the number of medications prescribed (P < 0·001) and an increasing trend in the number of long-term therapeutic groups (P < 0·001).  What is new and Conclusion: We describe the prevalence of clinically important DDIs in an emerging economy setting and identify the more common potentially serious DDIs. In line with the observations in developed economies, a higher number of episodes of DDIs were seen in patients aged ≥70 years and with more medications prescribed. The easiest method to reduce the frequency of DDIs is to reduce the number of medications prescribed. Therapeutic alternatives should be selected cautiously.

Acute poisoning is a common medical emergency in Malaysia. Life can be saved if the patient is diagnosed properly and receives the appropriate treatment such as gastrointestinal decontamination techniques and resources to increase poison elimination according to clinical guidelines at a reasonable time. The aims of this study were to determine the availability of decontamination, elimination enhancement, and stabilization resources for the management of acute toxic exposures and poisonings in accident and emergency departments in Malaysia, and to compare the availability of such facilities among various types of hospitals. A comparative, descriptive cross-sectional study was conducted using a structured questionnaire. Seventy-four (58.3%) out of the targeted 127 hospitals replied and completed the questionnaire. The availabilities of most items related to stabilization resources were far better in general hospitals compared to district hospitals with specialists and district hospitals without specialists. These items were mechanical ventilators (p = 0.011), non-invasive positive pressure ventilators (0.024), pacemakers (p = 0.019), and transcutaneous cardiac pacing (p < 0.001). The availability of decontamination resources varied substantially with hospital type. Nevertheless, these differences did not reach statistical significance in any of the cases, whereas sodium sulphate, sorbitol, and polyethylene glycol were almost never available. The availabilities of most items related to elimination enhancement resources were far better in general hospitals and district hospitals with specialists compared to district hospitals without specialists. These items were haemodialysis (p = 0.046), haemoperfusion (p = 0.002), haemofiltration (p = 0.002), acid diuresis (p = 0.04), peritoneal dialysis (p < 0.001), and exchange transfusion (p < 0.001). Most Malaysian hospitals have certain important immediate interventions such as gastrointestinal decontamination techniques and resources to increase poison elimination. The availabilities of most facilities were far better in the general hospitals. Coordination between the National Poison Centre in Malaysia and hospitals should be established regarding the emergency facilities for effective management of poisoning cases in each hospital in order to direct the poisoned patients to the hospital where the appropriate management resources is available.