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Spatial Model of Sky Brightness Magnitude in Langkawi Island, Malaysia

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Research in Astronomy and Astrophysics 2017年第4期17卷 57-66页

作者： Mohammad Redzuan Tahar Farahana Kamarudin roslan umar Mohd Khairul Amri Kamarudin Nor Hazmin Sabri Karzaman Ahmad Sobri Abdul Rahim Mohd Sharul Aikal Baharim Langkawi National Observatory Space Science Research Unit National Space Agency Empangan Bukit Malut 07000 Langkawi Kedah Malaysia East Coast Environmental Research Institute (ESERI) Universiti Sultan Zainal Abidin Gong Badak Campus 21300 Kuala Terengganu Terengganu Malaysia School of Fundamental Science Universiti Malaysia Terengganu 21030 Kuala Terengganu Terengganu Malaysia Department of Surveying Science and Geomatic Faculty of Architecture Planning and Surveying Universiti Teknologi Mara 02600 Arau Perlis Malaysia

Sky brightness is an essential topic in the field of astronomy, especially for optical astronom- ical observations that need very clear and dark sky conditions. This study presents the spatial model of sky brightness magnitude in Langkawi Island, Malaysia. Two types of Sky Quality Meter （SQM） manu- factured by Unihedron are used to measure the sky brightness on a moonless night （or when the Moon is below the horizon）, when the sky is cloudless and the locations are at least 100 m from the nearest light source. The selected locations are marked by their GPS coordinates. The sky brightness data obtained in this study were interpolated and analyzed using a Geographic Information System （GIS）, thus producing a spatial model of sky brightness that clearly shows the dark and bright sky areas in Langkawi Island. Surprisingly, our results show the existence of a few dark sites nearby areas of high human activity. The sky brightness of 21.45 mag arcsec-2 in the Johnson-Cousins V-band, as the average of sky brightness equivalent to 2.8 × 10-4cd m-2 over the entire island, is an indication that the island is, overall, still relatively dark. However, the amount of development taking place might reduce the number in the near future as the island is famous as a holiday destination.

关键词： light pollution - atlases - site testing - methods data analysis

Effects of synthesis parameters on the performance of crosslinked Co-polymers with clays for conformance control

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Petroleum Research 2024年第1期9卷 98-108页

作者： A.A.roslan N.A.A.Aziz N.F.A.Deraman I.Dzulkarnain Petroleum Engineering Department Centre of Research Enhanced Oil Recovery(COREOR)Universiti Teknologi PETRONASSeri IskandarPerakMalaysia Chemical Engineering Department Centre of Research Enhanced Oil Recovery(COREOR)Universiti Teknologi PETRONASSeri IskandarPerakMalaysia

Conformance control or water shut-off is a technique used to improve oil *** conformance control,polymers block high permeability water areas and redistribute water drive toward unswept oil *** this study,co-polymers(denoted ATP-PGV/AM-co-AMPS)were synthesized using acrylamide(AM)and 2-acrylamide-2-methylpropane sulfonic acid(AMPS)as the monomers,polyethylene glycol(PEG)-200 and methylenebisacrylamide(MBA)as the crosslinkers,attapulgite(ATP)and bentonite(PGV)as the clay types,and ammonium persulfate(APS)as the initiator,in addition to paraffin oil and *** were synthesized using inverse emulsion polymerization with different concentrations of monomers,crosslinkers,and clays,and they were characterized using Fourier-transform infrared(FTIR)spectroscopy and scanning electron microscopy(SEM)with energy dispersive X-ray spectroscopy(EDX).FTIR spectra of the samples confirmed the existence of sulfonate and hydroxyl groups,which are important for polymer ***-EDX images indicated that the morphology and elemental composition were different before and after swelling,confirming the occurrence of ***,samples were placed in sodium chloride solution(20,000 ppm)for 7 days to evaluate swelling at both room temperature and 90°*** analysis(TGA)and differential scanning calorimetry(DSC)were used to determine the thermal characteristics of the ***,rheological measurements were used to assess the deformation and rheological behavior of the *** results showed that after 1 day,good swelling without loss of mechanical strength was achieved with the composite synthesized using 10%AM,15%AMPS,6%PGV,and 10%ATP.

关键词： Polymer Clay Water shut-off Conformance Swelling

Effect of SrCO_3 addition on the dynamic compressive strength of ZTA

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International Journal of Minerals,Metallurgy and Materials 2016年第4期23卷 481-489页

作者： Ali Arab roslan Ahmad Zainal Arifin Ahmad School of Mechanical Engineering Universiti Sains Malaysia Engineering Campus Structural Materials Niche Area School of Materials and Mineral Resources Engineering Universiti Sains Malaysia Engineering Campus

Ceramic parts usually experience dynamic load in armor applications. Therefore, studying the dynamic behaviors of ceramics is important. Limited data are available on the dynamic behaviors of ceramics; thus, it is helpful to predict the dynamic strength of ceramics on the basis of their mechanical properties. In this paper, the addition of SrCO3 into zirconia-toughened alumina（ZTA） was demonstrated to improve the fracture toughness of ZTA due to the formation of the SrAl12O19（SA6） phase. The porosity of ZTA was found to be increased by the addition of SrCO3. These newly formed pores served as the nucleation sites of cracks under dynamic load; these cracks eventually coalesced to form damaged zones in the samples. Although the KIC values of the samples were improved, the dynamic strength was not enhanced because of the increase in porosity; in fact, the dynamic strength of ZTA ceramics decreased with the addition of SrCO3.

关键词： ceramics strontium carbonate dynamic properties fracture toughness compressive strength

Analysis of Distance-Based Topological Polynomials Associated with Zero-Divisor Graphs

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Computers, Materials & Continua 2022年第2期70卷 2895-2904页

作者： Ali Ahmad roslan Hasni Nahid Akhter Kashif Elahi College of Computer Sciences and Information Technology JazanJazan UniversitySaudi Arabia Faculty of Ocean Engineering Technology and Informatics University Malaysia TerengganuKuala Terengganu21030TerengganuMalaysia Department of Mathematics Govt.College UniversityLahorePakistan Deanship of E-learning and Information Technology Jazan UniversityJazanSaudi Arabia

Chemical compounds are modeled as *** atoms of molecules represent the graph vertices while chemical bonds between the atoms express the *** topological indices representing the molecular graph corresponds to the different chemical properties of *** a,b be are two positive integers,andΓ(Z_(a)×Z_(b))be the zero-divisor graph of the commutative ring Z_(a)×Z_(b).In this article some direct questions have been answered that can be utilized latterly in different *** study starts with simple computations,leading to a quite complex ring theoretic problems to prove certain *** theory of finite commutative rings is useful due to its different applications in the fields of advanced mechanics,communication theory,cryptography,combinatorics,algorithms analysis,and *** this paper we determine the distance-based topological polynomials and indices of the zero-divisor graph of the commutative ring Z_(p^(2))×Z_(q)(for p,q as prime numbers)with the help of graphical structure *** study outcomes help in understanding the fundamental relation between ring-theoretic and graph-theoretic properties of a zero-divisor graphΓ(G).

关键词： Zero divisor graph Wiener index Hosoya polynomial (modified)Schulz index (modified)Schulz polynomial

Integrated biological–physical process for biogas purification effluent treatment

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Journal of Environmental Sciences 2019年第9期31卷 110-122页

作者： roslan Noorain Tomonori Kindaichi Noriatsu Ozaki Yoshiteru Aoi Akiyoshi Ohashi Department of Civil and Environmental Engineering Graduate School of Engineering Hiroshima University 1-4-1 Kagamiyama Higashihiroshima Hiroshima 739-8527 Japan Section of Environmental Engineering Technology Malaysia Institute of Chemical & Bioengineering Technology University Kuala Lumpur Lot 1988 Kawasan Perindustrian Bandar Vendor Taboh Naning 78000 Alor Gajah Melaka Malaysia Department of Molecular Biotechnology Graduate School of Advanced Sciences of Matter Hiroshima University 1-3-1 Kagamiyama Higashihiroshima 739-8530 Japan

Biogas purification via water scrubbing produces effluent containing dissolved CH4, H2S,and CO2, which should be removed to reduce greenhouse gas emissions and increase its potential for water regeneration. In this study, a reactor built with air supplies at the top and bottom was utilized for the treatment of biogas purification effluent through biological oxidation and physical stripping processes. Up to 98% of CH4 was removed through biological treatment at a hydraulic retention time of 2 hr and an upper airflow rate of 2.02 L/day. Additionally, a minimum CH4 concentration of 0.04% with no trace of H2S gas was detected in the off gas. Meanwhile, a white precipitate was captured on the carrier showing the formation of sulfur. According to the developed mathematical model, an upper airflow rate of greater than 2.02 L/day showed a small deterioration in CH4 removal performance after reaching the maximum value, whereas a 50 L/day bottom airflow rate was required to strip the CO2 efficiently and raise the effluent p H from 5.64 to 7.3. Microbiological analysis confirmed the presence of type 1 methanotroph communities dominated by Methylobacter and Methylocaldum. However, bacterial communities promoting sulfide oxidation were dominated by Hyphomicrobium.

关键词： Biogas purification effluent Dissolved methane pH elevation Biological oxidation CO2 stripping

Total Restrained Bondage in Graphs

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Acta Mathematica Sinica,English Series 2013年第6期29卷 1033-1042页

作者： Nader JAFARI RAD roslan HASNI Joanna RACZEK Lutz VOLKMANN Department of Mathematics Shahrood University of Technology Department of Mathematics Faculty of Science and Technology University Malaysia Terengganu Department of Mathematics Gdansk University of Technology Lehrstuhl II fr Mathematik RWTH Aachen University

A subset S of vertices of a graph G with no isolated vertex is a total restrained dominating set if every vertex is adjacent to a vertex in S and every vertex in V （G） S is also adjacent to a vertex in V （G） S. The total restrained domination number of G is the minimum cardinality of a total restrained dominating set of G. In this paper we initiate the study of total restrained bondage in graphs. The total restrained bondage number in a graph G with no isolated vertex, is the minimum cardinality of a subset of edges E such that G E has no isolated vertex and the total restrained domination number of G E is greater than the total restrained domination number of G. We obtain several properties, exact values and bounds for the total restrained bondage number of a graph.

关键词： Domination total restrained domination bondage

Erosion risk assessment:A case study of the Langat River bank in Malaysia

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International Soil and Water Conservation Research 2017年第1期5卷 26-35页

作者： roslan Zainal Abidin Mohd Sofiyan Sulaiman Naimah Yusoff I-Geo Disaster Research Centre Infrastructure University Kuala LumpurJln Ikram-Uniten43000 KajangSelangorMalaysia

River bank erosion is one of the major and unpredictable hazards worldwide including in *** detachment at river banks is due to two processes:1)hydraulic erosion imposed by channel flow and 2)sub aerial erosion due to the weakening and weathering of bank *** paper is focused on the second aspect of the erosion process which mainly depends on the combination of rainfall intensity and the ability of the soil to withstand the raindrop *** relative combination of sand,silt and clay in a soil is argued to have an impact on erosion *** cohesive soil composition,sand forms the largest size ranging from 0.05 to 2 mm whereas silt is adequately moderate(ranging from 0.002 to 0.05 mm)and clay is the smallest of all three(less than 0.002 mm).With the knowledge that soil composition does indeed have an effect on erosion resistance,this paper will attempt to relate risk assessment index of river bank erosion specifically to soil ***,the objectives of this document are as follows;1)to produce risk assessment index for river bank erosion and 2)to carry out a case study for selected rivers in Malaysia pertaining to river bank *** index is produced by inferring the previously developed scale on soil *** researchers created the“ROM”scale(named after the researchers,Rolan and Mazidah)to assess degree of soil erodibility into five classes namely“critical”,“very high”,“high”,“medium”and“low”.Instead of using semi empirical formula from the“ROM”scale,a percentage of soil composition was inferred to produce risk assessment *** was found that as the percentage of clay decreased,susceptibility index became higher and approached a critical *** of the newly developed index is verified by conducting a case study at the Langat River,Kajang,*** soil composition was classified and form fitted into the *** was found that the middle reach of the Langat river is susceptible to severe erosion d

关键词： River bank erosion Percentage occupy Silt content Erodibility Shear stress

Assessment of rapid impact compaction in ground improvement from in-situ testing

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Journal of Central South University 2013年第3期20卷 786-790页

作者： M.M.Mohammed H.roslan S.Firas Department of Civil Engineering Faculty of EngineeringUniversity of MalayaKuala Lumpur 50603Malaysia

Ground improvement has been used on many construction sites to densify granular materials, in other word, to improve soil properties and reduce potential settlement. This work presents a case study of ground improvement using rapid impact compaction （RIC）. The research site comprises the construction of workshop and depots as part of railway development project at Batu Gajah-Ipoh, Malaysia. In-situ testing results show that the subsurface soil comprises mainly of sand and silty sand through the investigated depth extended to 10 m. Groundwater is approximately 0.5 m below the ground surface. Evaluation of improvement was based on the results of pre- and post-improvement cone penetration test （CPT）. Interpretation software has been used to infer soil properties. Load test was conducted to estimate soil settlement. It is found that the technique succeeds in improving soil properties namely the relative density increases from 45% to 70%, the friction angle of soil is increased by an average of 3°, and the soil settlement is reduced by 50%： The technique succeeds in improving soil properties to approximately 5.0 m in depth depending on soil uniformity with depth.

关键词： cone penetration test granular soil compaction rapid impact compaction relative density settlement improvement depth in-situ testing

Chromaticity of Complete 6-Partite Graphs with Certain Star or Matching Deleted Ⅱ

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Acta Mathematicae Applicatae Sinica 2013年第1期29卷 35-42页

作者： roslan Hasni Ameen Shaman Ameen Yee-Hock Peng Hai-xing Zhao School of Mathematical Sciences Universiti Sains Malaysia Department of Mathematics and Institute for Mathematical Research University Putra Malaysia Department of Mathematics Qinghai Normal University

Let P（G, λ） be the chromatic polynomial of a graph G. Two graphs G and H are said to be chromatically equivalent, denoted G N H, if P（G, λ） = P（H, λ）. We write [G] = {HIH - G}. If [G] = {G}, then G is said to be chromatically unique. In this paper, we first characterize certain complete 6-partite graphs with 6rid＋1 vertices according to the number of 7-independent partitions of G. Using these results, we investigate the chromaticity of G with certain star or matching deleted. As a by-product, many new families of chromatically unique complete 6-partite graphs with certain star or matching deleted are obtained.

关键词： chromatic polynomial chromatically closed chromatic uniqueness