This contribution investigates rain attenuation in Kuala Lumpur, Malaysia, by exploiting local Drop Size Distribution (DSD) measurements. Coefficients for the well- established power law model relating rain rate and specific attenuation are derived for frequencies in the Ku, Ka and Q/V bands based on three years of disdrometer data. We analyze the diurnal variation of rainfall rate for four time intervals, and, moreover, we present statistics of rain attenuation for slant path Earth-space links estimated by means of a new model (Stratiform-Convective SST) which combines the advantages of the Dual-Layer Synthetic Storm Technique (SST) and of the SC EXCELL model. The predicted statistics are in good agreement with those obtained from beacon measurements (MEASAT-1 satellite at 12 GHz). Finally, the diurnal variation of the slant path rain attenuation is presented to provide system operators and radio communication engineers with useful information on the Quality of Service (QoS) that can be achieved during a typical day on an Earth-space link

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In last decade, researchers have often tried to improve the usability, portability, integrity and other aspects of software in order for it to be more users friendly and gain user trust. Several approaches and techniques have been proposed to reduce the negative effects of software size and complexity. Moreover, several software quality models were proposed to evaluate general and specific type of software products. These models were proposed to evaluate general or specific scopes of software products. The proposed models were developed based on comparisons between the well-known models, in order to customize the closed model to the intended scope. These comparisons are leak of criteria that is conducted based on different perspectives and understanding. Therefore, a formal method of comparison between software quality models is proposed. The proposed method is applied on a comprehensive comparison between well-known software quality models. The result of the proposed method shows the strength and weaknesses of those models.

This work investigates the physical characteristics of raindrop size distribution (DSD) in an equatorial heavy rain region based on three years of disdrometer observations carried out at Universiti Teknologi Malaysia’s (UTM’s) campus in Kuala Lumpur, Malaysia. The natural characteristics of DSD are deduced, and the statistical results are found to be in accordance with the findings obtained from others disdrometer measurements. Moreover, the parameters of the Gamma distribution and the normalized Gamma model are also derived by means of method of moment (MoM) and maximum likelihood estimation (MLE). Their performances are subsequently validated using the rain rate estimation accuracy: the normalized Gamma model with the MLE-generated shape parameterµwas found to provide better accuracy in terms of long-term rainfall rate statistics, which reflects the peculiarities of the local climatology in this heavy rain region. These results not only offer a better understanding of the microphysical nature of precipitation in this heavy rain region but also provide essential information that may be useful for the scientific community regarding remote sensing and radio propagation.

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