Quality

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https://repoemc.ukm.my/handle/123456789/71

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Browsing Quality by Author "Abdul Aziz Jemain"

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    Perbandingan Pelbagai Kaedah Imputasi bagi Data Lenyap untuk Data Kualiti Udara
    (Penerbit UKM, 2015) Nuryazmin Ahmat Zainuri; Abdul Aziz Jemain; Nora Muda
    This paper presents various imputation methods for air quality data specifically in Malaysia. The main objective was to select the best method of imputation and to compare whether there was any difference in the methods used between stations in Peninsular Malaysia. Missing data for various cases are randomly simulated with 5, 10, 15, 20, 25 and 30% missing. Six methods used in this paper were mean and median substitution, expectation-maximization (EM) method, singular value decomposition (SVD), K-nearest neighbour (KNN) method and sequential K-nearest neighbour (SKNN) method. The performance of the imputations is compared using the performance indicator: The correlation coefficient (R), the index of agreement (d) and the mean absolute error (MAE).
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    Trend and status of air quality at three different monitoring stations in the Klang Valley, Malaysia
    (Springer, 2010) Siti Zawiyah Azmi; Mohd Talib Latif; Aida Shafawati Ismail; Liew Juneng; Abdul Aziz Jemain
    Over the last decades, the development of the Klang Valley (Malaysia), as an urban commercial and industrial area, has elevated the risk of atmospheric pollutions. There are several significant sources of air pollutants which vary depending on the background of the location they originate from. The aim of this study is to determine the trend and status of air quality and their correlation with the meteorological factors at different air quality monitoring stations in the Klang Valley. The data of five major air pollutants (PM10, CO, SO2, O3, NO2) were recorded at the Alam Sekitar Sdn Bhd (ASMA) monitoring stations in the Klang Valley, namely Petaling Jaya (S1), Shah Alam (S2) and Gombak (S3). The data from these three stations were compared with the data recorded at Jerantut, Pahang (B), a background station established by the Malaysian Department of Environment.