Displaying publications 81 - 100 of 121 in total

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  1. The relationship between vitamin D status and muscle strength in young healthy adults from sunny climate countries currently living in the northeast of Scotland
    Jamil NA, Gray SR, Fraser WD, Fielding S, Macdonald HM
    Osteoporos Int, 2017 04;28(4):1433-1443.
    PMID: 28083666 DOI: 10.1007/s00198-016-3901-3
    The current study examined the relationship between vitamin D status and muscle strength in young healthy adults: residents (>6 months) and newcomers (0-3 months), originally from sunny climate countries but currently living in the northeast of Scotland. Our longitudinal data found a positive, albeit small, relationship between vitamin D status and knee extensor isometric strength.

    INTRODUCTION: Vitamin D has been suggested to play a role in muscle health and function, but studies so far have been primarily in older populations for falls prevention and subsequent risk of fractures.

    METHODS: Vitamin D status was assessed in a healthy young adults from sunny climate countries (n = 71, aged 19-42 years) with 56% seen within 3 months of arriving in Aberdeen [newcomers; median (range) time living in the UK = 2 months (9-105 days)] and the remainder resident for >6 months [residents; 23 months (6-121 months)]. Participants attended visits every 3 months for 15 months. At each visit, fasted blood samples were collected for analysis of serum 25-hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH), carboxy-terminal collagen crosslinks (CTX) and N-terminal propeptide of type I collagen (P1NP). Maximal voluntary contractions (MVC) were performed for grip strength (both arms) and for maximal isometric strength of the knee extensors (right knee).

    RESULTS: There were small seasonal variations in 25(OH)D concentrations within the newcomers and residents, but no seasonal variation in bone turnover markers. There was a positive, albeit small, association between 25(OH)D and knee extensor maximal isometric strength. Mixed modelling predicted that for each 1 nmol/L increase in 25(OH)D, peak torque would increase by 1 Nm (p = 0.04).

    CONCLUSIONS: This study suggests that vitamin D may be important for muscle health in young adults migrating from sunnier climates to high latitudes, yet the potential effect is small.

    Matched MeSH terms: Sunlight
  2. Fulltext Numerical simulation on the reflection characterisation and performance of a solar collector - a case study of UP M Solar Bowl
    Ng, K.M., Adam, N.M., Azmi, B.Z.
    Pertanika Journal of Science & Technology, 2012;20(2):283-298.
    MyJurnal
    A numerical simulation of UPM Solar Bowl is presented in this paper. The numerical analysis considereda general model of solar bowl, which was divided into three modules: (a) reflection characterisation ofthe bowl, (b) solar flux density along the receiver, and (c) radiation contour mapping of the receiver.The governing equations are resolved in a segregated manner using Matlab programming environment.The influence of the tropical clear sky irradiance on the collector was numerically studied, whereas thecollector performance in time domain was also quantified. Single reflection is a major element in thermalconcentration. It was observed that solar flux density of collector substantially deteriorated during offsolar noon hour, in which during 08:00 and 16:00 under clear sky of tropics, the percentage reductionof flux density is over 82% at all points of the receiver. The simulated radiation contour mapping of thereceiver supports the finding. Other results of the UPM Solar Bowl simulation model are also shownand discussed.
    Matched MeSH terms: Sunlight
  3. Fulltext Analysis of absorber and buffer layer band gap grading on cigs thin film solar cell performance using SCAPS
    Nima Khoshsirat, Nurul Amziah Md Yunus, Mohd Nizar Hamidon, Suhaidi Shafie, Nowshad Amin
    Pertanika Journal of Science & Technology, 2015;23(2):241-250.
    MyJurnal
    A numerical simulation and analysis was performed to investigate the effect of absorber and buffer layer band gap grading and on a Copper-Indium-Gallium-Diselenide (CIGS) solar cell. The software used is the Solar Cell Capacitance Simulator (SCAPS). The absorber and buffer layer energy band structures’ effect on the cell’s output parameters such as open circuit voltage, short circuit current density, fill factor and efficiency were extensively simulated. Two structures of the energy band gap were simulated and studied for each of the absorber and buffer layer. The simulation was done on the uniform structure in which the energy band gap is constant throughout the layer. It was then continued on the cell with graded band structure, where the energy band gap of the material is varied throughout the layer. It was found that the cell with graded band structure in absorber and buffer layer had demonstrated higher efficiency and better performance in comparison with the cell with uniform band gap structure.
    Matched MeSH terms: Sunlight
  4. Fulltext Flat plate solar collectors and applications: a review
    Bande, Y. M., Mariah, N. A.
    Pertanika Journal of Science & Technology, 2014;22(2):365-385.
    MyJurnal
    In this study, various methods and applications of flat plate solar collectors are discussed and pictorial representations are presented. Low temperature applications of flat plate collectors are identified in solar cooking, solar water heating, space and air heating, industrial heating plants and in agricultural produce drying processes. Basic equations, as presented by many researchers in the performances of flat plate collectors, are also presented. The review discusses the analysis of losses from flat plate collectors towards obtaining the overall heat loss coefficient which indicate the performance of flat plate collectors.
    Matched MeSH terms: Sunlight
  5. Ozone-climate interactions and effects on solar ultraviolet radiation
    Bais AF, Bernhard G, McKenzie RL, Aucamp PJ, Young PJ, Ilyas M, et al.
    Photochem Photobiol Sci, 2019 Mar 01;18(3):602-640.
    PMID: 30810565 DOI: 10.1039/c8pp90059k
    This report assesses the effects of stratospheric ozone depletion and anticipated ozone recovery on the intensity of ultraviolet (UV) radiation at the Earth's surface. Interactions between changes in ozone and changes in climate, as well as their effects on UV radiation, are also considered. These evaluations focus mainly on new knowledge gained from research conducted during the last four years. Furthermore, drivers of changes in UV radiation other than ozone are discussed and their relative importance is assessed. The most important of these factors, namely clouds, aerosols and surface reflectivity, are related to changes in climate, and some of their effects on short- and long-term variations of UV radiation have already been identified from measurements. Finally, projected future developments in stratospheric ozone, climate, and other factors affecting UV radiation have been used to estimate changes in solar UV radiation from the present to the end of the 21st century. New instruments and methods have been assessed with respect to their ability to provide useful and accurate information for monitoring solar UV radiation at the Earth's surface and for determining relevant exposures of humans. Evidence since the last assessment reconfirms that systematic and accurate long-term measurements of UV radiation and stratospheric ozone are essential for assessing the effectiveness of the Montreal Protocol and its Amendments and adjustments. Finally, we have assessed aspects of UV radiation related to biological effects and human health, as well as implications for UV radiation from possible solar radiation management (geoengineering) methods to mitigate climate change.
    Matched MeSH terms: Sunlight
  6. Fulltext Technical Study of a Standalone Photovoltaic-Wind Energy Based Hybrid Power Supply Systems for Island Electrification in Malaysia
    Samrat NH, Ahmad N, Choudhury IA, Taha Z
    PLoS One, 2015;10(6):e0130678.
    PMID: 26121032 DOI: 10.1371/journal.pone.0130678
    Energy is one of the most important factors in the socioeconomic development of a country. In a developing country like Malaysia, the development of islands is mostly related to the availability of electric power. Power generated by renewable energy sources has recently become one of the most promising solutions for the electrification of islands and remote rural areas. But high dependency on weather conditions and the unpredictable nature of these renewable energy sources are the main drawbacks. To overcome this weakness, different green energy sources and power electronic converters need to be integrated with each other. This study presents a battery storage hybrid standalone photovoltaic-wind energy power supply system. In the proposed standalone hybrid system, a DC-DC buck-boost bidirectional converter controller is used to accumulates the surplus hybrid power in the battery bank and supplies this power to the load during the hybrid power shortage by maintaining the constant dc-link voltage. A three-phase voltage source inverter complex vector control scheme is used to control the load side voltage in terms of the voltage amplitude and frequency. Based on the simulation results obtained from MATLAB/Simulink, it has been found that the overall hybrid framework is capable of working under variable weather and load conditions.
    Matched MeSH terms: Sunlight
  7. Fulltext Integrated support vector regression and an improved particle swarm optimization-based model for solar radiation prediction
    Ghazvinian H, Mousavi SF, Karami H, Farzin S, Ehteram M, Hossain MS, et al.
    PLoS One, 2019;14(5):e0217634.
    PMID: 31150467 DOI: 10.1371/journal.pone.0217634
    Solar energy is a major type of renewable energy, and its estimation is important for decision-makers. This study introduces a new prediction model for solar radiation based on support vector regression (SVR) and the improved particle swarm optimization (IPSO) algorithm. The new version of algorithm attempts to enhance the global search ability for the PSO. In practice, the SVR method has a few parameters that should be determined through a trial-and-error procedure while developing the prediction model. This procedure usually leads to non-optimal choices for these parameters and, hence, poor prediction accuracy. Therefore, there is a need to integrate the SVR model with an optimization algorithm to achieve optimal choices for these parameters. Thus, the IPSO algorithm, as an optimizer is integrated with SVR to obtain optimal values for the SVR parameters. To examine the proposed model, two solar radiation stations, Adana, Antakya and Konya, in Turkey, are considered for this study. In addition, different models have been tested for this prediction, namely, the M5 tree model (M5T), genetic programming (GP), SVR integrated with four different optimization algorithms SVR-PSO, SVR-IPSO, Genetic Algorithm (SVR-GA), FireFly Algorithm (SVR-FFA) and the multivariate adaptive regression (MARS) model. The sensitivity analysis is performed to achieve the highest accuracy level of the prediction by choosing different input parameters. Several performance measuring indices have been considered to examine the efficiency of all the prediction methods. The results show that SVR-IPSO outperformed M5T and MARS.
    Matched MeSH terms: Sunlight*
  8. Fulltext DC-based smart PV-powered home energy management system based on voltage matching and RF module
    Sabry AH, Hasan WZW, Ab Kadir M, Radzi MAM, Shafie S
    PLoS One, 2017;12(9):e0185012.
    PMID: 28934271 DOI: 10.1371/journal.pone.0185012
    The main tool for measuring system efficiency in homes and offices is the energy monitoring of the household appliances' consumption. With the help of GUI through a PC or smart phone, there are various applications that can be developed for energy saving. This work describes the design and prototype implementation of a wireless PV-powered home energy management system under a DC-distribution environment, which allows remote monitoring of appliances' energy consumptions and power rate quality. The system can be managed by a central computer, which obtains the energy data based on XBee RF modules that access the sensor measurements of system components. The proposed integrated prototype framework is characterized by low power consumption due to the lack of components and consists of three layers: XBee-based circuit for processing and communication architecture, solar charge controller, and solar-battery-load matching layers. Six precise analogue channels for data monitoring are considered to cover the energy measurements. Voltage, current and temperature analogue signals were accessed directly from the remote XBee node to be sent in real time with a sampling frequency of 11-123 Hz to capture the possible surge power. The performance shows that the developed prototype proves the DC voltage matching concept and is able to provide accurate and precise results.
    Matched MeSH terms: Sunlight
  9. Fulltext Simple and efficient estimation of photovoltaic cells and modules parameters using approximation and correction technique
    Muhammad FF, Karim Sangawi AW, Hashim S, Ghoshal SK, Abdullah IK, Hameed SS
    PLoS One, 2019;14(5):e0216201.
    PMID: 31048867 DOI: 10.1371/journal.pone.0216201
    The behavior of solar cells and modules under various operational conditions can be determined effectively when their intrinsic parameters are accurately estimated and used to simulate the current-voltage (I-V) characteristics. This work proposed a new computational approach based on approximation and correction technique (ACT) for simple and efficient extraction of solar cells and modules parameters from the single-diode model. In this technique, an approximated value of series resistance (Rs) was first derived and used to determine the initial value of parallel resistance (Rp). Later, the final corrected values of Rs and Rp were obtained by resubstituting their approximated values in a five-loop iteration using the manipulated equations. For rapid evaluation and validation of the proposed technique, a software application was also created using MATLAB program. The correctness and robustness of the proposed technique was validated on five types of solar cells and modules operated at varied temperatures and irradiances. The lowest RMSE value was achieved for RTC France (7.78937E-4) and PVM 752 GaAs (2.10497E-4) solar cell. The legitimacy of ACT extracted parameters was established using a simple yet competitive implementation approach wherein the performance of the developed technique was compared with several state-of-the-art methods recently reported in the literature.
    Matched MeSH terms: Sunlight
  10. Fulltext Transparent Blend of Poly(Methylmethacrylate)/Cellulose Acetate Butyrate for the Protection from Ultraviolet
    Mahmood Raouf R, Abdul Wahab Z, Azowa Ibrahim N, Abidin Talib Z, Chieng BW
    Polymers (Basel), 2016 Apr 14;8(4).
    PMID: 30979233 DOI: 10.3390/polym8040128
    The use of transparent polymers as an alternative to glass has become widespread. However, the direct exposure of these materials to climatic conditions of sunlight and heat decrease the lifetime cost of these products. The aim of this study was to minimize the harm caused by ultraviolet (UV) radiation exposure to transparent poly(methylmethacrylate) (PMMA), which usually leads to changes in the physical and chemical properties of these materials and reduced performance. This was achieved using environmentally friendly cellulose acetate butyrate (CAB). The optical, morphological, and thermal properties of CAB blended with transparent PMMA was studied using UV-VIS spectrophotometry, scanning electron microscopy, X-ray diffraction, dynamic mechanical analysis, and thermal gravimetric analysis. The results show that CAB was able to reduce the effects of UV radiation by making PMMA more transparent to UV light, thereby preventing the negative effects of trapped radiation within the compositional structure, while maintaining the amorphous structure of the blend. The results also show that CAB blended with PMMA led to some properties commensurate with the requirements of research in terms of a slight increase in the value of the modulus and the glass transition temperature for the PMMA/CAB blend.
    Matched MeSH terms: Sunlight
  11. Variability in solar radiation and temperature explains observed patterns and trends in tree growth rates across four tropical forests
    Dong SX, Davies SJ, Ashton PS, Bunyavejchewin S, Supardi MN, Kassim AR, et al.
    Proc Biol Sci, 2012 Oct 7;279(1744):3923-31.
    PMID: 22833269
    The response of tropical forests to global climate variability and change remains poorly understood. Results from long-term studies of permanent forest plots have reported different, and in some cases opposing trends in tropical forest dynamics. In this study, we examined changes in tree growth rates at four long-term permanent tropical forest research plots in relation to variation in solar radiation, temperature and precipitation. Temporal variation in the stand-level growth rates measured at five-year intervals was found to be positively correlated with variation in incoming solar radiation and negatively related to temporal variation in night-time temperatures. Taken alone, neither solar radiation variability nor the effects of night-time temperatures can account for the observed temporal variation in tree growth rates across sites, but when considered together, these two climate variables account for most of the observed temporal variability in tree growth rates. Further analysis indicates that the stand-level response is primarily driven by the responses of smaller-sized trees (less than 20 cm in diameter). The combined temperature and radiation responses identified in this study provide a potential explanation for the conflicting patterns in tree growth rates found in previous studies.
    Matched MeSH terms: Sunlight
  12. Fulltext Coral mass spawning predicted by rapid seasonal rise in ocean temperature
    Keith SA, Maynard JA, Edwards AJ, Guest JR, Bauman AG, van Hooidonk R, et al.
    Proc Biol Sci, 2016 05 11;283(1830).
    PMID: 27170709 DOI: 10.1098/rspb.2016.0011
    Coral spawning times have been linked to multiple environmental factors; however, to what extent these factors act as generalized cues across multiple species and large spatial scales is unknown. We used a unique dataset of coral spawning from 34 reefs in the Indian and Pacific Oceans to test if month of spawning and peak spawning month in assemblages of Acropora spp. can be predicted by sea surface temperature (SST), photosynthetically available radiation, wind speed, current speed, rainfall or sunset time. Contrary to the classic view that high mean SST initiates coral spawning, we found rapid increases in SST to be the best predictor in both cases (month of spawning: R(2) = 0.73, peak: R(2) = 0.62). Our findings suggest that a rapid increase in SST provides the dominant proximate cue for coral mass spawning over large geographical scales. We hypothesize that coral spawning is ultimately timed to ensure optimal fertilization success.
    Matched MeSH terms: Sunlight
  13. Estimated vitamin D synthesis and dietary vitamin D intake among Asians in two distinct geographical locations (Kuala Lumpur, 3°N v. Aberdeen, 57°N) and climates
    Jamil NA, Yew MH, Noor Hafizah Y, Gray SR, Poh BK, Macdonald HM
    Public Health Nutr, 2018 Dec;21(17):3118-3124.
    PMID: 30176950 DOI: 10.1017/S1368980018002057
    OBJECTIVE: To compare the contributions of UVB exposure and diet to total vitamin D among Asians living in Kuala Lumpur (KL) and Aberdeen (AB).

    DESIGN: Longitudinal study.

    SETTING: UVB exposure (using polysulfone film badges) and skin colour and dietary vitamin D intake (by web-based questionnaire) were measured at each season in AB and during south-west (SWM) and north-east monsoons (NEM) in KL.

    SUBJECTS: One hundred and fifteen Asians in KL and eighty-five Asians in AB aged 20-50 years.

    RESULTS: Median summer UVB exposure of Asians in AB (0·25 SED/d) was higher than UVB exposure for the KL participants (SWM=0·20 SED/d, P=0·02; NEM= 0·14 SED/d, P<0·01). UVB exposure was the major source of vitamin D in KL year-round (60%) but only during summer in AB (59%). Median dietary vitamin D intake was higher in AB (3·50 µg/d (140 IU/d)), year-round, than in KL (SWM=2·05 µg/d (82 IU/d); NEM=1·83 µg/d (73 IU/d), P<0·01). Median total vitamin D (UVB plus diet) was higher in AB only during summer (8·45 µg/d (338 IU/d)) compared with KL (SWM=6·03 µg/d (241 IU/d), P=0·04; NEM=5·35 µg/d (214 IU/d), P<0·01), with a comparable intake across the full year (AB=5·75 µg/d (230 IU/d); KL=6·15 µg/d (246 IU/d), P=0·78).

    CONCLUSIONS: UVB exposure among Asians in their home country is low. For Asians residing at the northerly latitude of Scotland, acquiring vitamin D needs from UVB exposure alone (except in summer) may be challenging due to low ambient UVB in AB (available only from April to October).

    Matched MeSH terms: Sunlight*
  14. Energy, exergy and efficiency analysis of a flat plate solar collector used as air heater
    Maazullah Khan, Abdurab, Muhammad Hanif, Mansoor Khan Khattak, Muhammad Ramzan
    Sains Malaysiana, 2018;47:1061-1067.
    Air heating by solar collectors is renewable technology providing hot air for different purposes. The present research
    emphasizes on analysis of energy, exergy and efficiency of a flat plate solar air heater. The analysis model was tested
    on five different air mass flow rates of 0.5 (Natural), 1.31, 2.11, 2.72 and 3.03 kgs-1 under three different tilt angles of
    25, 35 (Recommended) and 50o
    . The data was replicated three times making a total of 45 treatments. A two factorial
    completely randomized design was used to find if there is any significant difference among the treatments. The results
    showed that the solar collector gave better performance at air mass flow of 3.03 kgs-1 under tilt of 35o
    . At maximum
    air mass flow rate of 3.03 kgs-1and optimum tilt angle of 35o
    the maximum energetic efficiency of 51%, while minimum
    exergetic efficiency of 24% and maximum overall efficiency of 71% were recorded. It was concluded that to get maximum
    thermal efficiencies of 71% from flat plate solar collector used as an air heater must be operated at high air mass flow
    rates of 3.03 kgs-1under 35o
    tilt angle at Peshawar, Pakistan.
    Matched MeSH terms: Sunlight
  15. Decolorization and Mineralization of Batik Wastewater through Solar Photocatalytic Process
    Wan Fadhilah Khalik, Ong SA, Wong YS, Nik Athirah Yusoff, Fahmi Ridwan, Ho LN
    Sains Malaysiana, 2015;44:607-612.
    In this study, the photocatalytic degradation of batik wastewater in the presence of zinc oxide (ZnO) as photocatalyst was
    investigated. The effect of various operating parameters, such as pH of batik wastewater, catalyst dosage and aeration
    on the photocatalytic degradation process, was examined. The mineralization of batik wastewater was also evaluated
    through chemical oxygen demand analysis. The decolorization of batik wastewater was enhanced at acidic conditions
    (pH3) which was 88.2% after 10 h irradiated under solar light, meanwhile its mineralization was 286 mg/L after 12 h
    irradiation time. The data obtained for photocatalytic degradation of batik wastewater was well fitted with the LangmuirHinshelwood
    kinetic model. It can be concluded that batik wastewater could be decolorized and mineralized under solar
    light irradiation with presence of ZnO.
    Matched MeSH terms: Sunlight
  16. Effect of light intensity and fertiliser levels on the stock plants of chengal (neobalanocarpus heimii) and rooting of its subsequent cuttings
    Aminah H, Naimah C, Rajabarizan R, Mohd Noor M
    Sains Malaysiana, 2013;42:257-263.
    A factorial experiment of three light intensities and three fertiliser levels was carried out on the potted seedlings of neobalanocarpus heimii as stock plants for subsequent rooting of cuttings. Light intensities used were 25%, 50% and 100% of the open sunlight and the fertilizer levels were 0 g, 1 g and 2 g plant-1 month-1. Results of 11 months after potting showed that the stock plants treated with 1 g and 2 g fertilizer had significantly better height and diameter increments than those without fertilizer in all light intensities tried. On the other hand, no significant effect of light intensity was obtained in height and diameter increments of the stock plants. Survival of stock plants of more than 86% was obtained in all light intensities tried with or without fertilizer application. Test on rooting of subsequent cuttings showed that light intensity of 25% and 0 g fertiliser, to stock plants gave the highest rooting percentage (73%) and the number of roots (2.0). The general trend showed that rooting decreased to below 60% when intensity of light was increased. In terms of size, cuttings with diameter between 1.2 mm and 2.3 mm is recommended as it yielded rooting of 65% to 75%. For practical application, a combination of 25% light intensity and 1 g of fertilizer plant-1 month-1 can be applied to the stock plants to maintain their healthy growth for continuous production of cutting materials for rooting.
    Matched MeSH terms: Sunlight
  17. Development of an efficient flat plate solar air heater for drying and water heating purposes
    Hanif M, Khattak M, Amin M, Ramzan M, Zakir S, Ullah S, et al.
    Sains Malaysiana, 2016;45:489-497.
    A 1.7 m2 flat plate solar air heater was designed and developed in the Department of Agricultural Mechanization, The University of Agriculture Peshawar, Pakistan in collaboration with the Department of Environmental Sciences, University of Peshawar, Pakistan. It was operated under an average solar irradiance of 0.9 kJ.m-2.h-1 in the month of September, 2013. It worked under an efficiency of 7.5 to 21%. The heat collected by the air heater was given to air flowing as a medium inside it. This hot air was given to a drying section and water heating tank for drying and water heating purposes. The drying section provided a temperature in the range of 40-50oC and humidity of 10-30% from 10:00 am to 3:00 pm. The water heating tank provides hot water with a temperature of 35- 45oC from 10:00 am to 5:00 pm. Furthermore, the drying section was used to dry apples, onions and persimmons. All the products showed a consistent moisture loss from them with an optimum drying rate. The two term exponential model showed that all the three products dried have a good correlation with drying time with R2 values higher than 0.90. It was concluded that flat plate solar air heaters is the best technology for water heating and drying purposes and is a good alternative of conventional energy sources.
    Matched MeSH terms: Sunlight
  18. Developing correlation equations for converting among coliforms, E. coli and HPC for rainwater disinfection by sunlight
    M.T. Amin, M.Y. Han, Tschung-il Kim, A.A. Alazba, M.N. Amin
    Sains Malaysiana, 2013;42:1273-1281.
    The application of solar disinfection for treating stored rainwater was investigated by the authors using indicator organisms. The multiple tube fermentation technique and pour plate method were used for the detection of microbial quality indicators like total and fecal coliforms, E. coli and heterotrophic plate count. These techniques have disadvantages mainly that these are laborious and time consuming. The correlation of total coliform with that of exposure time is proposed under different factors of weather, pH and turbidity. Statistical tools like root mean square error and coefficient of determination were used to validate these proposed equations. The correlation equations of fecal coliform, E. coli and heterotrophic plate count with total coliform are suggested by using four regression analysis including Reciprocal Quadratic, Polynomial Regression (2 degree), Gaussian Model and Linear Regression in order to reduce the tedious experimental work in similar types of experiments and treatment systems.
    Matched MeSH terms: Sunlight
  19. Feedforward backpropagation, Genetic Algorithm approaches for predicting reference evapotranspiration
    Shafika Sultan Abdullah, M.A. Malek, Namiq Sultan Abdullah, A. Mustapha
    Sains Malaysiana, 2015;44:1053-1059.
    Water scarcity is a global concern, as the demand for water is increasing tremendously and poor management of water resources will accelerates dramatically the depletion of available water. The precise prediction of evapotranspiration (ET), that consumes almost 100% of the supplied irrigation water, is one of the goals that should be adopted in order to avoid more squandering of water especially in arid and semiarid regions. The capabilities of feedforward backpropagation neural networks (FFBP) in predicting reference evapotranspiration (ET0) are evaluated in this paper in comparison with the empirical FAO Penman-Monteith (P-M) equation, later a model of FFBP+Genetic Algorithm (GA) is implemented for the same evaluation purpose. The study location is the main station in Iraq, namely Baghdad Station. Records of weather variables from the related meteorological station, including monthly mean records of maximum air temperature (Tmax), minimum air temperature (Tmin), sunshine hours (Rn), relative humidity (Rh) and wind speed (U2), from the related meteorological station are used in the prediction of ET0 values. The performance of both simulation models were evaluated using statistical coefficients such as the root of mean squared error (RMSE), mean absolute error (MAE) and coefficient of determination (R2). The results of both models are promising, however the hybrid model shows higher efficiency in predicting ET0 and could be recommended for modeling of ET0 in arid and semiarid regions.
    Matched MeSH terms: Sunlight
  20. Innovative dual storage heat tank combination solar thermal, air conditioners and heat pump of water heating systems
    Chen WL, Wong KL, Li YC
    Sains Malaysiana, 2015;44:1707-1714.
    Tropical or subtropical countries are very suitable for the development of solar and heat pump technology. This paper
    proposed the integration of air conditioners that exhaust heat with solar energy to enhance the overall efficiency of thermal
    energy conversion. The analysis of thermal storage tanks of different volumes showed that a two-ton air conditioner
    operating for an hour produced double energy than normal sunshine for a day. With thermal storage tanks of fixed
    volume, the integration of air conditioners of different tons with solar energy indicated that air conditioners of less tons
    produced faster and more efficient energy conversion. Therefore, this paper proposed that the modification of condenser
    in domestic air conditioner into water-cooled condenser not only enhance the energy efficiency of air conditioners but
    also increased hot water supplies since hot water from air conditioners could be integrated into solar water heaters. By
    doing so, energy conservation and carbon reduction could be achieved.
    Matched MeSH terms: Sunlight
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