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81.
Sri Atmaja P. Rosyidi Mohd Raihan Taha Zamri Chik Amiruddin Ismail 《Acta Geophysica》2009,57(3):616-635
Surface wave method consists of measurement and processing of the dispersive Rayleigh waves recorded from two or more vertical
transducers. The dispersive phase data are inverted and the shear wave velocity versus depth is obtained. However, in case of residual soil, the reliable phase spectrum curve is difficult to be produced. Noises
from nature and other human-made sources disturb the generated surface wave data. In this paper, a continuous wavelet transform
based on mother wavelet of Gaussian Derivative was used to analyze seismic waves in different frequency and time. Time-frequency
wavelet spectrum was employed to localize the interested seismic response spectrum of generated surface waves. It can also
distinguish the fundamental mode of the surface wave from the higher modes of reflected body waves. The results presented
in this paper showed that the wavelet analysis is able to determine reliable surface wave spectrum of sandy clayey residual
soil. 相似文献
82.
Mokhtar Ernieza Suhana Pradhan Biswajeet Ghazali Abd Halim Shafri Helmi Zulhaidi Mohd 《Natural Hazards》2017,87(2):1125-1146
Natural Hazards - Discharge is traditionally measured at gauge stations located at discrete positions along the river course. When the volume of water discharge is higher than the river bank,... 相似文献
83.
Mohd Sofiyan Sulaiman Shanker Kumar Sinnakaudan Nik Nuraini Azhari Roslan Zainal Abidin 《Environmental Earth Sciences》2017,76(7):300
Mountain rivers and lowland rivers differ in many ways. Some of the many elements that distinguish both river systems apart are the rivers’ geomorphological appearances, hydraulic geometry, pollution transport, sediment transport, and its own roughness and coarseness. In this particular study, the element of sediment transport is given distinctive attention too. This study employs the deterministic approach for bed load prediction entailing the use of the parameterization concept where particle size and flow variation is taken into full consideration. Apart from that, the classical approach of Shields number is also used to determine the transport rates at the fluvial system. However, due to some limitation and range of applicability, the Shields number approach was re-modified to suit the range of applicability. Changes were made to the alleviating critical stress term and formulating exponential approach. For this research, it was important to deduce the underlying principles which are universal and common to all river systems, due to obvious and distinct differences between the mountain and lowland rivers. A special attribute was given to the Malaysian natural rivers because of the limited recorded data available. All datasets were compiled and tested with the bed load predictors to observe the commonality pattern between the lowland and mountain river systems. Most of the bed load transport equations limit the range of applicability by isolating the flow regime or bed roughness individually. Thus, it was vital for researchers to find the commonality pattern between these two river systems which needed to be statistically sound in its form. It was postulated that the particle densimetric Froude number is graphically and statistically fit for both river systems. Hence, this predictor is used as it has a high potential to be included in the sediment transport parameterization for Malaysian natural rivers. 相似文献
84.
Abdul Rani Abdullah Norhayati Mohd. Tahir Tong Soo Loong Tafazzal Mohd. Hoque Abdul Halim Sulaiman 《Marine pollution bulletin》1999,39(1-12):229-233
The Straits of Malacca is subjected to a great variety of environmental stresses due to its strategic location as a major international shipping lane and the concentration of agriculture, industry and urbanisation which predominate on the west coast of Peninsular Malaysia. This paper gives an overview of the study conducted in the Malacca Straits as part of the GEF/UNDP/IMO Regional Programme on the Prevention and Management of Marine Pollution in the East Asian Seas, in particular pertaining to the identification of land and sea-based sources of pollution in Malaysia which contributes to the pollution load in the Straits, as well as the assessment of the relative contribution of each source. 相似文献
85.
86.
87.
In the first part the number of independent non-vanishing components of the 3-index torsion tensorQ
jk
i
is reduced from 24 (in general case) to 12 — for the case of cylindrical symmetry of the underlying manifold. In the second part of the paper we have obtained an exact solution of Einstein-Cartan-Maxwell equations representing a static cylinder of perfect fluid with an axial magnetic fieldH and non-zero spin densityK. 相似文献
88.
Syed Mustafizur Rahman Md. Omar Faruk Md. Habibur Rahman Mumnunul Keramat Mohd Nawawi Faisal Kamal Zaidi 《Arabian Journal of Geosciences》2016,9(13):623
The crustal structure beneath three seismic stations over Malaysia has been investigated with the application of the group velocity dispersion analysis of the northern Sumatra earthquake data which occurred on 06 April 2010. Eighteen crustal layer models are constructed to assess the structure. Group velocity dispersions have been computed for the recorded earthquake data using a graphical method and modified Haskell matrix method for the models. Both dispersions have been presented for the interpretation of crustal layers. Findings have shown four major crustal layers having thicknesses of 2.5–4.0, 2.0–5.5, 5.0–8.0, and 8.5–9.0 km, while in Terengganu, it has shown three layers. Density, shear, and compressional wave velocities used in models have suggested that the crustal structure of the northern part of Peninsular Malaysia is crystalline. Major crustal minerals are of quartz, plagioclase, and mica. Most layers seem to have upward directions toward Perak from Kedah and Terengganu. 相似文献
89.
Naveen Kumar Tirumalesh Keesari S. Chidambaram Shyam Ranjan Mohd Soheb 《水文科学杂志》2013,58(11):1717-1732
ABSTRACTThe temporal variations in electrical conductivity and the stable isotopes of water, δD and δ18O, were examined at Chhota Shigri Glacier, India, to understand water sources and flow paths to discharge. Discharge is highly influenced by supraglacially derived meltwater during peak ablation, and subglacial meltwaters are more prominent at the end of the melt season. The slope of the best fit linear regression line for δD versus δ18O, for both supraglacial and runoff water, is lower than that for precipitation (snow and rain) and surface ice, indicating strong isotopic fractionation associated with the melting processes. The slope of the local meteoric water line (LMWL) is close to that of the global meteoric water line (GMWL), reflecting that the moisture source is predominantly oceanic. The d-excess variation in rainwater confirms that the southwest monsoon is the main contributor during summer while the remainder including winter is mostly influenced by westerlies. 相似文献
90.
H. Ismail A. K. Abd Wahab M. F. Mohd Amin M. Z. Mohd Yunus F. Jaffar Sidek B. Esfandier J. 《Natural Hazards》2012,63(2):549-573
The 2004 tsunami that struck the Sumatra coast gave a warning sign to Malaysia that it is no longer regarded as safe from a future tsunami attack. Since the event, the Malaysian Government has formulated its plan of action by developing an integrated tsunami vulnerability assessment technique to determine the vulnerability levels of each sector along the 520-km-long coastline of the north-west coast of Peninsular Malaysia. The scope of assessment is focused on the vulnerability of the physical characteristics of the coastal area, and the vulnerability of the built environment in the area that includes building structures and infrastructures. The assessment was conducted in three distinct stages which stretched across from a macro-scale assessment to several local-scale and finally a micro-scale assessment. On a macro-scale assessment, Tsunami Impact Classification Maps were constructed based on the results of the tsunami propagation modelling of the various tsunami source scenarios. At this stage, highly impacted areas were selected for an assessment of the local hazards in the form of local flood maps based on the inundation modelling output. Tsunami heights and flood depths obtained from these maps were then used to produce the Tsunami Physical Vulnerability Index (PVI) maps. These maps recognize sectors within the selected areas that are highly vulnerable to a maximum tsunami run-up and flood event. The final stage is the development of the Structural Vulnerability Index (SVI) maps, which may qualitatively and quantitatively capture the physical and economic resources that are in the tsunami inundation zone during the worst-case scenario event. The results of the assessment in the form of GIS-based Tsunami-prone Vulnerability Index (PVI and SVI) maps are able to differentiate between the various levels of vulnerability, based on the tsunami height and inundation, the various levels of impact severity towards existing building structures, property and land use, and also indicate the resources and human settlements within the study area. Most importantly, the maps could help planners to establish a zoning scheme for potential coastline development based on its sensitivity to tsunami. As a result, some recommendations on evacuation routes and tsunami shelters in the potentially affected areas were also proposed to the Government as a tool for relief agencies to plan for safe evacuation. 相似文献