Displaying publications 21 - 40 of 2561 in total

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  1. Abd. Rahim Samsudin, Umar Hamzah, Abd. Ghani Rafek, Haryono
    The whole Bachok area is covered by alluvial deposit. The alluvium has three aquifers at depth of 0 - 5, 15 - 30 and 40 - 60 meters below surface. Preliminary geophysical surveys including seismic refraction, reflection and resistivity techniques have been carried out to investigate thickness and depth of the aquifers, depth of bedrock and the salinity of the underground water. Results show that the position of first aquifer has been well determined by seismic refraction technique. Whereas the details of deeper aquifers and the bedrock have been determined by seismic reflection techniques. Geoelectrical resistivity low obtained for the first aquifer suggest that it could be due to either salt water intrusion or the presence of marine clay.
    Keseluruhan kawasan Bachok merupakan endapan aluvium. Endapan ini mempunyai tiga akuifer pada kedalaman 0 - 5 meter, 15 - 30 meter dan 40 - 60 meter. Kajian geofizik pada tahap awal yang merangkumi aspek seismos biasan, seismos pantulan dan kerintangan geoelektrik telah dilakukan untuk menyiasat ketebalan dan kedalaman akuifer, kedalaman batu dasar dan kemasinan air tanah. Hasil kajian menunjukkan bahawa teknik seismos biasan telah dapat menghasilkan maklumat mengenai kedudukan akuifer pertama. manakala teknik seismos pantulan menghasilkan maklumat terperinci mengenai akuifer kedua dan ketiga serta batu dasar. Nilai kerintangan geoelektrik rendah bagi akuifer pertama menunjukkan sama ada disebabkan oleh intrusi air masin atau kehadiran lempung samudera.
  2. Abd. Rahim Samsudin, Umar Hamzah, Rakmi Abdul Rahman
    The hot springs of Peninsular Malaysia were studied to gather information on their associated geology, temperature, flow rate and water quality as well as to assess their potential development for tourism industry. The geological study indicated that most of the hot springs are located within or close to the granite rock and associated with fault zones. The temperature of the hot springs range from 27°C to 103°C with individual flow rate between 0.1 to 27.0 L/S. Chemical analysis indicated that all of the hot spring waters are relatively low in dissolved salts and metals.
    Kajian menyeluruh ke atas mata air panas di Semenanjung Malaysia telah dilakukan untuk mendapatkan maklumat geologi, suhu, kadar aliran dan kualiti air panas serta potensi untuk dibangunkan bagi industri pelancongan. Kajian geologi menunjukkan kebanyakan mata air panas ini terletak di dalam atau berhampiran kawasan batuan granit dan berasosiasi dengan zon sesar. Air panas ini mempunyai julat suhu daripada 27°C hingga 103°C dan kadar aliran daripada 0.1 hingga 27.0 L/S. Analisis kimia menunjukkan kesemua air panas ini mengandungi kandungan garam dan logam terlarut yang rendah.
  3. Abdul Aziz Ahmad, Raihan Othman, Faridah Yusof, Mohd Firdaus Abdul Wahab
    Sains Malaysiana, 2014;43:459-465.
    A hybrid biofuel cell, a zinc-air cell employing laccase as the oxygen reduction catalyst is investigated. A simple cell design is employed; a membraneless single chamber and a freely suspended laccase in the buffer electrolyte. The cell is characterised based on its open-circuit voltage, power density profile and galvanostatic discharge at 0.5 mA. The activity of laccase as an oxidoreductase is substantiated from the cell discharge profiles. The use of air electrode in the cell design enhanced the energy output by 14%. The zinc-air biofuel cell registered an open-circuit voltage of 1.2 V and is capable to deliver a maximum power density of 1.1 mWcm-2 at 0.4 V. Despite its simple design features, the power output is comparable to that of biocatalytic cell utilising a much more complex system design.
  4. Abdul Aziz Jemain, Al-Omari A, Kamarulzaman Ibrahim
    McIntyre was the first to suggest ranked set sampling (RSS) method for estimating the population mean. In this paper, we modify RSS to come up with new sampling method, namely, two stage ranked set sampling (TSRSS) for samples of size m=3k (k=1,2,..). The TSRSS is suggested for estimating the population median in order to increase the efficiency of the estimators. The TSRSS was compared to the simple random sampling (SRS), ranked set sampling (RSS), extreme ranked set sampling (ERSS), median ranked set sampling (MRSS) and balance groups ranked set sampling (BGRSS) methods. It is found that, TSRSS gives an unbiased estimator of the population median of symmetric distributions and it is more efficient than SRS. Also, it is more efficient than RSS, ERSS, MRSS and BGRSS based on the same number of measured units. For asymmetric distributions considered in this study, TSRSS has a small bias and smaller variance than SRS, RSS, ERSS, MRSS and BGRSS methods.
  5. Abdul Aziz Jemain
    This paper presents the accuracy of age statistics in the 1991 census. The quality of age statistics were evaluated using Myers index and United Nations index. The indices obtained were compared to the indices of 1970 and 1980. This study found that age statistics for 1991 census are better than the previous censuses and in general the statistics are having high quality.
    Dalam kertas ini dibentangkan ketepatan statistik umur pada banci 1991. Kualiti statistik umur dinilai dengan menggunakan indeks Myers dan United Nations. Indeks yang diperoleh dibandingkan dengan indeks pada banci 1970 dan 1980. Kajian ini mendapati statistik umur banci 1991 lebih baik daripada hasil banci sebelumnya dan pada keseluruhannya ia mempunyai kualiti yang baik.
  6. Abdul Aziz Jemain
    This paper offers a technique to create a development index among districts. To determine the weight for each criterion in the index entropy theory was used. Two approaches for criteria normalization were also suggested. The data obtained from 1991 census conducted in Peninsular Malaysia were utilized as illustration.
    Kertas ini mencadangkan teknik pembinaan indeks kemajuan daerah. Teori entropy digunakan untuk menentukan pemberat bagi kriteria yang digunakan dalam pembinaan indeks. Dua pendekatan menormalkan data turut dicadangkan. Contoh pembinaan indeks dikemukakan berdasarkan kemudahan asas yang terdapat di daerah-daerah di Semenanjung Malaysia seperti yang diperoleh berdasarkan banci tahun 1991.
  7. Abdul Fattah Abu Bakar, Siti Nathasa Md Barkawi, Marlia Mohd. Hanafiah, Lee KE, Azhar Abdul Halim
    Sains Malaysiana, 2016;45:1509-1516.
    Keberkesanan rawatan air sisa industri automotif ditentukan dengan menggunakan kaedah penjerapan turus. Peratusan penyingkiran ammonia dan logam berat terpilih telah dikaji menggunakan pasir biasa dan pasir terubah suai secara kimia sebagai bahan penjerap. Dua model matematik iaitu Model Thomas serta Model Yoon-Nelson telah digunakan untuk menentukan kapasiti penjerapan maksimum ammonia. Peratusan penyingkiran ammonia menunjukkan pasir terubah suai secara kimia mencatatkan julat peratusan penyingkiran yang lebih tinggi iaitu 43.68% hingga 96.55% berbanding pasir biasa yang mencatatkan julat 0% hingga 89.66%. Logam berat zink, mangan, kromium, kuprum, arsenik, nikel, kobalt dan ferum mencatatkan peratusan penyingkiran antara 93% hingga 100% apabila menggunakan pasir terubah suai secara kimia manakala pasir biasa mencatatkan julat peratusan penyingkiran daripada 0.8% hingga 100%. Keputusan analisis menggunakan Model Thomas menunjukkan kapasiti penjerapan maksimum, qo ammonia menggunakan pasir terubah suai secara kimia (8.80 mg/g) adalah empat kali lebih tinggi daripada pasir biasa (2.57 mg/g) manakala masa bolos, t0.5 bahan penjerap yang ditentukan menggunakan Model Yoon dan Nelson mencatatkan masa tertinggi bagi pasir terubah suai secara kimia iaitu 30.18 min berbanding 9.57 min bagi pasir biasa. Kajian ini menunjukkan peratusan penyingkiran dan kapasiti penjerapan ammonia dan logam berat terpilih iaitu zink, mangan, kuprum, arsenik, nikel, kobalt dan ferum lebih tinggi bagi turus pasir terubah suai secara kimia berbanding pasir biasa.
  8. Abdul Ghani Rafek, Azimah Hussin, Lee KE, Ailie Sofyiana Serasa, Goh TL
    Sains Malaysiana, 2016;45:185-193.
    The uniaxial compressive strength (UCS) is one of the most common mechanical parameters required in geotechnical engineering to characterize the compressive strength of rock material. Measurements of UCS are expensive, time consuming, destructive and thus, not favorable in the presence of limited samples. Therefore, a simple yet practical application is needed for the estimation of UCS. This research presents two correlations to predict UCS values for granite and schist by using ultrasonic velocity travel time (tp) from ultrasonic tests. The validity of the practical approach presented in this research is confirmed based on the strong correlations developed from the experimental tests conducted. For the entire data set, the correlation between UCS and ultrasonic velocity travel time was expressed as UCS = 217.2 e-0.016(tp) for granite and UCS = 1110.6 e-0.037(tp) for schist and the coefficient of determination (R2) value for both granite and schist is 0.93. These correlations may be useful for applications related to geotechnical engineering designs.
  9. Abdul Ghani Rafek, Khairuddin Nordin
    The new Genting Sempah tunnel represents an important part of the widening and upgrading of the main east-west road link between Kuala Lumpur on the west coast and Kuantan on the east coast of Peninsular Malaysia. The new tunnel is located between 18m to 30m north of the existing (old) tunnel which was constructed in 1975 and has a similar alignment. Engineering geological investigations and site characterization for the construction of the new tunnel were carried out in 1994 with drilling, aerial photograph interpretation, surface geological mapping, geophysical surveys and laboratory testing. Rock mass classification was carried out based on the Q classification system of Barton et at. (1974). Based on this classification, it was predicted that for the tunnel zone, 8.6 % of the length of the tunnel consisted of rock mass classified as very poor i.e. type two, 82.8% as extremely poor, i.e. type three and the remaining 8.6% as exceptionally poor, i.e. type four. Excavation of the tunnel between March 1995 and September 1996 together with engineering geological logging and rock mass classification revealed the following; type two, very poor 6.3%, type three, extremely poor 89.9%, type four, exceptionally poor 3.8%. These results show the general validity of the prediction of the rock mass quality.
    Terowong kedua Genting Sempah merupakan suatu bahagian utama dalam pembesaran dan peningkatan taraf jalan timur-barat utama yang menghubungi Kuala Lumpur di pantai barat dan Kuantan di pantai timur Semenanjung Malaysia. Terowong kedua berkedudukan 18 m hingga 30 m ke utara terowong lama yang dibina pada tahun 1975 dan mempunyai penjajaran yang sama. Penyiasatan geologi kejuruteraan dan pemeriksaan tapak pembinaan terowong kedua dilaksanakan pada tahun 1994 dengan penggerudian, pentafsiran fotograf udara, pemetaan geologi permukaan, survei geofizik dan ujian makmal. Pengelasan kualiti jasad batuan dilakukan berdasarkan sistem pengelasan Q oleh Barton et al. (1974). Hasil pengelasan ini di zon terowong meramalkan 8.6% panjang terowong baru terdiri daripada jasad batuan berkualiti sangat rendah, iaitu jenis dua, 82.8% berkualiti tersangat rendah, iaitu jenis tiga manakala 8.6% panjang terowong terdiri daripada jasad batuan berkualiti luarbiasa rendah, iaitu jenis empat. Penggalian terowong di antara Mac 1995 dan September 1996 dengan rakaman geologi kejuruteraan dan pengelasan jasad batuan semasa penggalian menghasilkan keputusan seperti berikut; jenis dua, berkualiti sangat rendah 6.3%, jenis tiga, berkualiti tersangat rendah 89.9%, jenis empat, berkualiti luar biasa rendah 3.8%. Keputusan
  10. Abdul Ghapor Hussin, Ali H.M. Abu Zaid, Adriana Irawaty Nur Ibrahim, Adzhar Rambli
    Sains Malaysiana, 2013;42:869-874.
    The existence of outliers in any type of data affects the estimation of models’ parameters. To date there are very few literatures on outlier detection tests in circular regression and it motivated us to propose simple techniques to detect any outliers. This paper considered the complex linear regression model to fit circular data. The complex residuals of complex linear regression model were expressed in two different ways in order to detect possible outliers. Numerical example of the wind direction data was used to illustrate the efficiency of proposed procedures. The results were very much in agreement with the results obtained by using the circular residuals of the simple regression model for circular variables.
  11. Abdul Ghapor Hussin, Norli Anida Abdullah, Ibrahim Mohamed
    This paper gives a comprehensive discussion on complex regression model by extending the idea of regression model to circular variables. Various aspect have been considered such as the biasness of parameters, error assumptions and model checking. The advantage of this approach is that it allows the use of usual technique available in ordinary linear regression for the regression of circular variables. The quality of the estimates and the feasibility of the approach were illustrated via simulation. The model was then applied to the wave direction data.
  12. Abdul Hafiz Ab Majid, Abu Hassan Ahmad
    Sains Malaysiana, 2015;44:211-216.
    Termites are one of the social insects living in large colonies that can cause economic loss. The objective of this study was to estimate foraging territory of infested subterranean termites on building structure. A mark-recapture study was conducted on eight Coptotermes gestroi colonies located at selected infested building structures in Penang, Malaysia. From the foraging study, the population of C. gestroi was estimated to be within the range of 106,592±6,968 to 4,185,000±2,127,328. Additionally, the foraging territory was from 13 to 300 m2 of the infested building structures. Meanwhile the maximum foraging distance was from 4 to 30 m of the infested structures. The results indicated that each of the building structures was infested by a single colony. This study also showed that the triple mark recapture technique used to estimate the population size of the termite colony was capable of providing rough estimates of foraging population of C. gestroi.
  13. Abdul Halim Abdul Gafor, Rozita Mohd, Rizna Cader, Kong Wei Yen, Marlyn Mohamad, Shamsul Azhar Shah, et al.
    Sains Malaysiana, 2018;47:149-155.
    Cardiovascular disease (CVD) is a major cause of morbidity and mortality in chronic kidney disease (CKD) patients. This study aimed to determine the roles of CVD biomarkers in CKD patients. This was a case-control study which recruited consecutive patients with stage 2-4 CKD patients with and without CVD. Serum levels of highly-sensitive C reactive protein (hs-CRP), cystatin C (CysC), asymmetrical dimetylarginine (ADMA) and symmetrical dimethylarginine (SDMA) were measured. Sixty two stage 2-4 CKD patients with a mean age of 60.3 ± 10.4 years were recruited. Twenty three (37.1%) of them had CVD. Those CKD patients with CVD were older (64.1±8.0 vs 58.1± 1.1, p<0.05) and had significantly higher systolic blood pressure (139.4 ± 16.2 vs 129.4 ± 14.8 mmHg, p<0.05). Diabetic patients had 8 times (95% CI 1.25-51.77, p< 0.05) higher risk to develop CVD. CKD patients with CVD had a higher serum creatinine (185.0 ± 54.1 vs 154.1 ± 54.4 μmol/L, p<0.05), a lower estimated glomerular filtration rate (33.7 ± 12.2 vs 42.2 ± 14.5 mL/min/1.73m2 p<0.05) and a lower triglyceride levels (1.3 (1.1-1.7) vs 1.8 (1.4-2.3) mmol/L, p<0.05), compared to those without CVD. Fasting blood sugar was 7.1 ± 2.7 mmol/L in CVD group and 6.3 ± 1.6 mmol/L in non CVD group (p>0.05). There were no differences in their mean serum levels of hs-CRP, CysC, ADMA and SDMA. Risk factors including age, diabetes mellitus, hypertension and renal functions were still the most important CVD risk factors in CKD patients.
  14. Abdul Halim Abdullah, Wong WY, Mohd Ismail Yaziz
    The decolorization of reactive orange 16 dye (RO16) from aqueous solution by CuO/H2O2 was investigated. The amount of dye removed was determined by measuring the concentration of the dye at its characteristic wavelengths by UV-Vis spectrophotometer. The effects of CuO dose, H2O2 concentration and UV light on the decolorization of the dye were investigated. It was found that the removal rate increased with increasing mass of CuO and increasing concentration of H2O2. The combination of CuO, H2O2 and UV light was the best system with dye removal of 100% after 6 h. The removal efficiency observed was in the order: CuO/UV/H2O2 > CuO/H2O2 > CuO/UV = CuO > UV/H2O2 > H2O2 > UV.
  15. Abdul Hamid Othman, Ibrahim Baba, Yang Farina Abdul Aziz, Norman Awang
    Several triphenylphosphinosilver (I) complexes, viz. bis [acetatotriphenylphosphineargentum (I)], I, lactatotris (triphenylphosphine) argentum (I), II, N, N-diethanoldithiocarbamatobis (triphenylphosphine) silver (I), III, and N­ethanol, N-methyldithiocarbamatobis (triphenylphosphine) silver (I), IV, have been prepared. Apart from characterization by spectroscopic methods, the structures of I-III, have been characterised by single-crystal x-ray diffraction methods. I crystallized as a dimer with a 4-coordinate geometry around the silver atom, while the lactate complex is a monomer with a five-coordinate silver atom. In the four-coordinate complex III, the Ag - S bond distances are 2.6822 (13) and 2.5991 (12) Å indicating different modes of bonding to the dithiocarbamate ligands.
    Beberapa kompleks trifenilfosfinoargentum telah disintesis, iaitu bis [asetatotrifenilfosfinargentum (I)], I, laktatotris (trifenilfosfin) argentum (I), II dietanolditiokarbamatobis (trifenilfosfin) argentum (I), III dan metiletanolditiokarbamatobis (trifenilfosfin) argentum (I), IV. Selain daripada pencirian dengan kaedqh spektroskopi, struktur kompleks I-III telah ditentukan dengan kaedah pembelauan sinar-X hablur tunggal. Kompleks asetat terhablur sebagai dimer dengan argentum menunjukkan geomertri 4-koordinat, sementara kompleks laktat adalah monomer dengan argentum berkoordinatan lima. Dalam kompleks dietanolditiokarbamat argentum berkoordinatan empat dengan panjang ikatan Ag - S, 2.6822 (13) dan 2.5991 (12) Ã… menunjukkan dua mod pengikatan yang berbeza dengan ditiokarbamat.
  16. Abdul Kadir R, Amer Siddiq A, Yahya N, Rusdi A, Hazli Z, Hussain H
    Sains Malaysiana, 2013;42:1-5.
    This study assess the effective use of audience response system (ARS), an interactive presenter-audience electronic system, in measuring Malaysian dentists’ interest in attending a less explored non-clinical continuing professional education topic. A total of 157 dentists voluntarily attended a specially designed one-day-four-module workshop conducted in four urban locations. The effective use of ARS in commanding attendance was measured in terms of dentists’ full seminar attendance to completion and opinion regarding the use of the instrument. The retention rate of workshop attendance to completion in the four locations ranged between 76.5 and 100%. Out of these participants, 93.7% said they enjoyed the ARS approach, 92.4% agreed it motivated them to stay on until the end, 97% said it increased their curiosity and appreciates answering in anonymity. The use of ARS technology is effective in enhancing participants’ interest and retention in the workshop, provides interactive learning opportunities and quick feedback and has a potential as an objective instrument in research data collection.
  17. Abdul Khalil HPS, Md. Sohrab Hossain, Nur Amiranajwa AS, Nurul Fazita MR, Mohamad Haafiz MK, Suraya N, et al.
    Sains Malaysiana, 2016;45:833-839.
    This present study was conducted to produce defatted oil palm shell (OPS) nanoparticles. Wherein, the OPS nanoparticles
    were defatted by solvent extraction method. Several analytical methods including transmission electron microscope (TEM),
    X-ray diffraction (XRD), particle size analyzer, scanning electron microscope (SEM), SEM energy dispersive X-ray (SEM-EDX)
    and thermal gravimetric analyzer (TGA) were used to characterize the untreated and defatted OPS nanoparticles. It was
    found that 75.3% OPS particles were converted into nanoparticles during ball milling. The obtained OPS nanoparticles had
    smaller surface area with angular, irregular and crushed shapes under SEM view. The defatted OPS nanoparticles did not
    show any agglomeration during TEM observation. However, the untreated OPS nanoparticles had higher decomposition
    temperature as compared to the defatted OPS nanoparticles. Based on the characterization results of the OPS nanoparticles,
    it is evident that the defatted OPS nanoparticles has the potentiality to be used as filler in biocomposites
  18. Abdul Munir Abdul Murad, Rafidah Badrun, Sakina Shahabudin, Shazilah Kamaruddin, Madihah Ahmad Zairun, Farahayu Khairuddin, et al.
    Sains Malaysiana, 2013;42:715-724.
    Kitin merupakan polisakarida struktur yang dapat dicurai oleh enzim kitinolisis kepada pelbagai terbitan yang boleh digunakan dalam bidang perubatan, pertanian dan rawatan air. Pengenalpastian dan pencirian gen-gen Trichoderma virens UKM1 mengekod enzim terlibat dalam pencuraian kitin krustasea telah dilakukan melalui penjanaan penanda jujukan terekspres (ESTs) dan analisis pengekspresan gen menggunakan mikroatur DNA. Sebanyak tiga perpustakaan cDNA T. virens UKM1 yang masing-masing diaruh oleh kitin, glukosamina dan kitosan telah dibina. Sejumlah 1536 klon cDNA telah dijujuk dan sebanyak 1033 ESTs berkualiti telah dijana. Seterusnya, perbezaan pengekspresan gen apabila pertumbuhan kulat diaruh dengan kehadiran kitin krustasea dan tanpa kitin pada hari ketiga dan kelima telah ditentukan. Sebanyak 1824 klon cDNA telah dititik ke atas slaid kaca dan dihibrid bersama dengan cDNA terlabel Cy3 atau Cy5 yang disintesis daripada mRNA yang dipencil daripada kulat yang ditumbuhkan dalam medium mengandungi kitin krustasea atau glukosa (kawalan). Sebanyak 91 dan 61 gen, masing-masing bagi hari ketiga dan kelima didapati terekspres melebihi dua gandaan apabila kulat menggunakan kitin krustasea sebagai sumber karbon. Beberapa gen mengekod kitinase seperti ech1 dan cht3 (endokitinase), nag1 (eksokitinase) dan nagB (glukosamina 6-P-deaminase) didapati terekspres dengan tinggi pada kedua-dua hari. Selain daripada itu, gen mengekod protein hidrofobin, protease serina dan beberapa protein hipotetik juga terekspres dengan tinggi dengan kehadiran kitin krustasea. Protein-protein ini dijangka memainkan peranan penting dalam membantu pencuraian kitin krustasea.
  19. Abdul Rahim Samsuddin, Abdul Ghani Rafek, Umar Hamzah, Suharsono, Khairul Anuar Mohd Nayan
    Analisis spektrum gelombang permukaan (SASW) adalah kaedah seismos yang menggunakan ciri serakan gelombang Rayleigh yang merambat pada lapisan bahan bagi memperolehi profil halaju gelombang ricih. Kaedah SASW merupakan satu kaedah insitu tanpa musnah untuk pencirian tapak geoteknik yang lebih kos efektif berbanding kaedah konvensyenal secara penggerudian. Dalam kajian ini sebanyak 20 stesen yang terdiri daripada 13 tapak kajian telah dipilih. Perisian (WINSASW 2.0) telah digunakan dalam proses penyongsangan untuk menghasilkan profil halaju gelombang ricih melawan kedalaman. Profil-profil ini kemudian dianalisis secara berasingan bagi memperolehi beberapa parameter geologi kejuruteraan jasad batuan seperti kekukuhan, nilai Penanda Mutu Batuan (RQD), anisotropi dan sifat kebolehkorekan. Analisis data SASW dijalankan dengan menganggap bahawa jasad batuan adalah homogen dan isotrop serta mengandungi pelbagai intensiti ketakselanjaran yang mempengaruhi perambatan halaju gelombang permukaan. Pengukuran sifat kedinamikan tanah dijalankan dengan menggunakan halaju gelombang ricih dan nilai ketukan N daripada Ujian Penusukan Piawai (NSPT) dalam lubang gerudi. Satu persamaan linear baharu, Vs = 4.44 NSPT + 213.84 yang mengaitkan halaju gelombang ricih dan NSPT telah diperolehi. Satu persamaan empirik telah dikemukakan bagi mengukur nilai Penanda Mutu Batuan (RQD) berasaskan halaju gelombang ricih yang diperolehi daripada kaedah SASW dan halaju daripada ujian ultrasonik. Persamaan ini memberikan hasil yang perbezaannya kurang daripada 10% berbanding data RQD daripada lubang gerudi. Analisis keanisotropan jasad batuan dijalankan menggunakan halaju gelombang ricih yang diperolehi berdasarkan kaedah SASW yang diukur dalam empat arah. Plot nisbah halaju gelombang ricih - halaju ultrasonik melawan halaju ultrasonik telah digunakan untuk menentukan sifat kebolehkorekan jasad batuan. Sebanyak lima kelas lengkungan kebolehkorekan jasad batuan telah dapat dikemukakan iaitu lengkungan Mudah korek, Mudah koyak, Susah koyak, Pemecah hidraulik dan Peletupan.
  20. Abdul Rahim Samsudin, Umar Hamzah, Zuraidah Ramli
    Sains Malaysiana, 2007;36:159-163.
    An integrated geophysical study was conducted to investigate the subsurface regional structure and the presence of a Quaternary sedimentary basin in the Olak Lempit - Banting area of Selangor, Malaysia. A regional gravity survey and the high resolution reflection seismic were employed to determine the thickness and areal distribution of the alluvial sedimentary basin as well as to investigate the depth and topography of the bedrock in the study area. The sedimentary basin hosts one of the most important coastal alluvial aquifer which was used to cater the shortage of domestic water supply during the worst water crisis that hit the state of Selangor in 1998. The surface geological map shows that in general 70% of the study area is covered by Quaternary deposits of Beruas, Gula and Simpang Formations which overlie the sedimentary bedrock of Kenny Hill Formation. The Beruas Formation consists of mainly clay, sandy clay and peat of Holocene fluviatile-estuarine deposits, whereas the Gula Formation represents Holocene marine to estuarine sediments which mostly consists of clay and minor sand. The Simpang Formation (Pleistocene) is a continental deposit comprising of gravel, sand, clay and silt. The underlying Kenny Hill Formation consists of a monotonous sequence of interbedded shales, mudstones and sandstones. The rock is Carbonaceous in age and it forms an undulating surface topography in the eastern part of the study area. A total of 121 gravity stations were established using a La Coste & Romberg gravity meter and the elevations of most of the stations were determined barometrically using Tiernan-Wallace altimeters. The high resolution seismic reflection using the common mid point (CMP) or roll along technique was carried out using a 24 channel signal enhancement seismograph and high frequency geophones. A total length of about 1.7 km stacked seismic section has been acquired in this survey and a nearby borehole data was used for interpretation. A relative Bouguer anomaly map shows an elongated zone of low gravity anomaly trending approximately NW-SE which is interpreted to be the deposition center of the Quaternary basin. The interpreted gravity profiles running across the central area of the study area show that the basin has thickness varies from tenth to several hundred meters with maximum depth to bedrock of about 275m. A gravity profile which passes through the eastern edge of the basin was modeled with depth to bedrock of about 178m below ground which agrees very well with those obtained from the interpreted seicmic section and borehole data. The stacked seismic section shows several high amplitude parallel to sub-parallel reflection overlying discontinuos and low reflection pattern. Reflections on the eastern part of the section is much shallower than the one observed on the western part which clearly indicates the presence of basinal structure with a total interpreted depth to bedrock of about 200 meters.
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