Roslan Umar

Bio: Roslan Umar is an academic researcher from Universiti Sultan Zainal Abidin. The author has contributed to research in topics: Radio astronomy & Radio telescope. The author has an hindex of 14, co-authored 91 publications receiving 814 citations. Previous affiliations of Roslan Umar include Universiti Teknologi MARA & University of Malaya.

A review of biomass-derived heterogeneous catalyst for a sustainable biodiesel production

Abstract: Biodiesel production is commonly carried out through the process of transesterification reaction. The reaction is expedited with a suitable catalyst either homogeneous or heterogeneous. The selection of an appropriate catalyst depends on the amount of free fatty acids in the oil. Recently, homogeneous catalysts are widely chosen for biodiesel production in large scale operation. However, they are toxic, highly flammable and corrosive in nature. Furthermore, the use of homogeneous catalyst produced soaps as by-product and large amount of wastewater that required additional processing technologies and cost for proper disposal. On the contrary, heterogeneous catalysts are capable to overcome the problems faced by the former ones. However, they were mostly derived from non-renewable resources, highly expensive with low stability. Recently, heterogeneous catalysts derived from biological waste have gotten more attention. This type of catalysts offers several advantages, including renewable resources, non-toxic, reusable, high catalytic activity, stability in both acidic and basic conditions and high water tolerance properties, which depend on the amount and strengths of active acid or basic sites. Basic catalyst can be subdivided based on the type of metal oxides and their derivatives. Similarly, acidic catalyst can be subdivided depending upon their active acidic sites. In this article, efforts have been taken to review the bio-based heterogeneous catalyst utilized for sustainable biodiesel production and their suitability for industrial application. Catalyst generated from bio-waste and other biocatalysts, which are heterogeneous in nature and extensively reported in literature are also reviewed. The utilization of these biomass derived catalysts provides a greener synthesis route for biodiesel production.

Assessment of Total Suspended Sediment and Bed Sediment Grains in Upstream Areas of Lata Berangin, Terengganu

Abstract: The amount of suspended sediment yield and the size of sediment grains an indicator of hydrological cycle, especially in the river The sediment transportation process is one of the measurements of water resources management Equilibrium of the river depends on the flow rate of water and by several factors such as frequency of rainfall, climate changes and land use activities that changes then effected to the river flow Sedimentation problems occur in reservoirs, rivers, lakes, flood plains and offshore This study was carried out in the upstream area, Lata Berangin, Hulu Keruak, Besut, Terengganu This study was implemented to prove the sedimentation problem, especially the formation of total suspended sediment (TSS) and the bed sediment grain size There are three important parameters were quantified in this study such as the distribution of sediment grain size (phi), TSS (mg/L) and the river discharge values (Q) (m³/s) The technique of analysis of primary data obtained which determine the bed sediment grain size according with the procedure of Gerald and Kenneth and the phi (ϕ) value in this study using the scale Udden-Wentworth that included median, mean, standard deviation, skewness, kurtosis and the Gravimetric Method used to analyze the concentration TSS is the Gravimetric Method From the result, the highest TSS up to 60 mg/L which is categorized under the class I, based on the National Water Quality Standard Overall, the estimated daily-suspended sediment load values up to 11649 tonne/day at Station 2 Then, from the statistics for the median, mean, standard deviation, skewness and kurtosis showed that the size of sediment falls between phi -030φ to phi -100 φ which classified as very coarse and the majority of the sediment texture and a very leptokurtic, leptokurtic texture showed sedimentation production is not so high Overall, the sedimentation problem in Lata Berangin, Hulu Keruak still in stable level Most of this upstream area still not developed as land use activities around the river basin

Identification source of variation on regional impact of air quality pattern using chemometric

Abstract: This study intends to show the effectiveness of hierarchical agglomerative cluster analysis (HACA), discriminant analysis (DA), principal component analysis (PCA), factor analysis (FA) and multiple linear regressions (MLR) for assessing the air quality data and air pollution sources pattern recognition. The data sets of air quality for 12 months (January–December) in 2007, consisting of 14 stations around Peninsular Malaysia with 14 parameters (168 datasets) were applied. Three significant clusters - low pollution source (LPS) region, moderate pollution source (MPS) region, and slightly high pollution source (SHPS) region were generated via HACA. Forward stepwise of DA managed to discriminate 8 variables, whereas backward stepwise of DA managed to discriminate 9 out of 14 variables. The method of PCA and FA has identified 8 pollutants in LPS and SHPS respectively, as well as 11 pollutants in MPS region, where most of the pollutants are expected derived from industrial activities, transportation and agriculture systems. Four MLR models show that PM10 categorize as the primary pollutant in Malaysia. From the study, it can be stipulated that the application of chemometric techniques can disclose meaningful information on the spatial variability of a large and complex air quality data. A clearer review about the air quality and a novel design of air quality monitoring network for better management of air pollution can be achieved.

Mitigation and Adaptation Strategies for Global Change

Abstract: ▶ Addresses a wide range of timely environment, economic and energy topics ▶ A forum to review, analyze and stimulate the development, testing and implementation of mitigation and adaptation strategies at regional, national and global scales ▶ Contributes to real-time policy analysis and development as national and international policies and agreements are discussed and promulgated ▶ 94% of authors who answered a survey reported that they would definitely publish or probably publish in the journal again

Interferometry And Synthesis In Radio Astronomy

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Tourism: a community approach

Abstract: guidance\" (p. xii). They have to some extent succeeded in their objectives. Certainly the compilation of references related to aesthetics and visual resources is a valuable contribution in itsell As is evident from this reader’s perspective, however, the poor organization and execution of the book unhappily detract from its effectiveness. Nora Laughlin is the Forest Landscape Architect and Assistant Recreation Staff on the Six Rivers National Forest, Eureka, California 95501.