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In Alborz Mountains, the thickness of sediments in Member 2 of the Mila Formation (Middle Cambrian) underwent dramatic and
abrupt deformations, which were accompanied by normal and reverse faults and asymmetrical folds. These deformed sediments
are covered by parallel beds both in the upper and lower sides. The existence of such extension and compression structures
adjacent to each other indicates the influence of non-tectonic factors in their evolution. These deformations induced by downslope
gliding of sediment packages are fully compatible with the dislocation model of Farrell (J Struct Geol 6:727–736, 1984) and Farrell and Eaton (1987). Moreover, the occurrence of synsedimentary deformations in a vast area in Alborz Mountains reinforces the probability of
the impact of seismic shocks in their formation. In fact, incessant seismic events in the Middle Cambrian led to numerous
submarine slumpings in the sediments of Member 2 of the Mila Formation. 相似文献
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ABSTRACTThis study assesses the performance of Fourier series in representing seasonal variations of the tropical rainfall process in Malaysia. Fourier series are incorporated into a spatial-temporal stochastic model in an attempt to make the model parsimonious and, at the same time, capture the annual variation of rainfall distribution. In view of Malaysia’s main rainfall regime, the model is individually fitted for two regions with distinctive rainfall profiles: one being an urban area receiving rainfall from convective activities whilst the other receives rainfall from monsoonal activities. Since both regions are susceptible to floods, the study focuses on the rainfall process at fine resolution. Fourier series equations are developed to represent the model’s parameters to describe their annual periodicity. The number of significant harmonics for each parameter is determined by inspecting the cumulative fraction of total variance explained by the significant harmonics. Results reveal that the number of significant harmonics assigned for the parameters is slightly higher in the region with monsoonal rains. The overall simulation results show that the proposed model is capable of generating tropical rainfall series from convective and monsoonal activities.
Editor D. Koutsoyiannis Associate editor K. Hamed 相似文献
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Noorhazlina Abu BakarKheng Soo Tay Nasr Yousef M.J. OmarM. Radzi Bin Abas Bernd R.T. Simoneit 《Applied Geochemistry》2011,26(8):1433-1445
The molecular distributions of homologous aliphatic lipid compounds (n-alkanes, n-alkanoic acids, n-alkanols, n-alkanals and n-alkan-2-ones) were investigated in sediments of Lake Bera, Malaysia as well as in plant waxes from the vicinity using gas chromatography-mass spectrometry. In addition, triterpenoids of the oleanane, ursane, lupane and friedelane series, and their diagenetic products were also identified. Using the aquatic proxy Paq, it was found that the n-alkanes present in surface sediments S1, S5 and S6 correspond to an input from emergent macrophytes, whereas in sediments collected from open water (S2, S3 and S4) they correspond to input from submerged/floating macrophytes. The presence of n-alkan-2-ols, a commonly found homologous series in the sediments as well as in the plant wax, is novel here. In addition, the presence of 24-methylcycloart-22-enol and 24-ethylcycloart-22-enol in sediments as well as the plant wax of Pandanus helicopus, a dominant reed around the lake, also supports the input of plant biomarkers to the sediments. The occurrence of 5-membered ring triterpenoid derivatives as major diagenetic products of the triterpenoids identified (e.g. friedelan-2,3-dione) shows that the degradation of the organic matter in the sediments occurs mainly under oxic conditions. Also, the presence of ring-A degraded triterpenoids (dihydroputranjivic acid, 3-nor-2,4-seco-friedelane, 4α- and 4β-3-norfriedelanes, A-norfriedel-10-one, and A-norfriedel-8-en-10-one) and the aromatized triterpenoid hydrocarbons (mono- and triaromatic derivatives) as minor diagenetic products indicates photochemical and microorganism-mediated alteration reactions of natural products in the sediments. Additional novel polyfunctional friedelane derivatives, namely friedelane-2,3-dione, friedelane-1,3-diol-2-one and friedel-1(10)-ene-1,3-diol-2-one were identified for the first time in this study. These novel polyfunctional triterpenoids were inferred to derive from the oxidation of the triterpenoids from higher plants in this oxic tropical environment. For future reference purposes, the mass spectra of the identified polar triterpenoids are also presented here. This study provides important data on the biogeochemistry of organic matter in a tropical lake of SE Asia. 相似文献
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M. A. Fagier E. A. Ali K. S. Tay M. R. B. Abas 《International Journal of Environmental Science and Technology》2016,13(4):1189-1194
Application of advanced oxidation process for wastewater treatment has gained more attention recently. In this study, the efficiency of coagulation–flocculation pretreatment coupled with sulfate radical-based advanced oxidation process (SR-AOP) in the removal and mineralization of organic matter of sugarcane vinasse was evaluated. For coagulation–flocculation, jar-test experiment was carried out with ferric chloride as coagulant and the removal of TOC, color and UV254 was determined. The results revealed that by using 15 g/L of coagulant, 70 % of TOC removal and nearly 100 % of UV254 and color removal were achieved. The pretreated vinasse was then subjected to SR-AOP. In this study, sulfate radical was generated using persulfate (PS) and peroxymonosulfate (PMS) activated by Fe(II). The effect of reaction time, oxidants to Fe(II) ratio and pH on the TOC removal efficiency were investigated. For the effect of reaction time, the TOC removal was found to increase significantly for the first 5 min. TOC removal was found to increase with increasing concentration of Fe(II) for PMS. However, for Fe(II)/PS, the TOC removal efficiency was decreased with increasing Fe(II) concentration. Both Fe(II)/PMS and Fe(II)/PS showed the highest TOC removal efficiency when the oxidation was carried out at pH 7. By using the selected optimum condition, nearly 70 and 49 % of TOC removal were achieved for PMS/Fe(II) and PS/Fe(II), respectively. Therefore, it can be concluded that SR-AOP can be a promising alternative method for TOC removal from sugarcane vinasse. 相似文献
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Ng Fei Chong Zawawi Mohd Hafiz Azman Aqil Abas Aizat Razak Norizham Abdul Aziz Nurhanani A. Zahari Nazirul Mubin 《Ocean Dynamics》2022,72(2):99-114
Ocean Dynamics - In this paper, a two-phase coastal liquid-sediment system and a wave breaker were numerically simulated using a particle-based smooth particle hydrodynamics (SPH). To verify the... 相似文献
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Norzaida Abas Zalina M. Daud Fadhilah Yusof 《Theoretical and Applied Climatology》2014,118(3):597-607
A stochastic rainfall model is presented for the generation of hourly rainfall data in an urban area in Malaysia. In view of the high temporal and spatial variability of rainfall within the tropical rain belt, the Spatial–Temporal Neyman–Scott Rectangular Pulse model was used. The model, which is governed by the Neyman–Scott process, employs a reasonable number of parameters to represent the physical attributes of rainfall. A common approach is to attach each attribute to a mathematical distribution. With respect to rain cell intensity, this study proposes the use of a mixed exponential distribution. The performance of the proposed model was compared to a model that employs the Weibull distribution. Hourly and daily rainfall data from four stations in the Damansara River basin in Malaysia were used as input to the models, and simulations of hourly series were performed for an independent site within the basin. The performance of the models was assessed based on how closely the statistical characteristics of the simulated series resembled the statistics of the observed series. The findings obtained based on graphical representation revealed that the statistical characteristics of the simulated series for both models compared reasonably well with the observed series. However, a further assessment using the AIC, BIC and RMSE showed that the proposed model yields better results. The results of this study indicate that for tropical climates, the proposed model, using a mixed exponential distribution, is the best choice for generation of synthetic data for ungauged sites or for sites with insufficient data within the limit of the fitted region. 相似文献
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K. S. Tay N. A. Rahman M. R. Bin Abas 《International Journal of Environmental Science and Technology》2013,10(1):103-112
A study was undertaken in order to understand the kinetics and mechanism of the chemical oxidation of N,N-diethyl-m-toluamide, an insect repellent, by sulfate radical. In this experiment, sulfate radical was generated using peroxymonosulfate with iron(II) and cobalt(II) as activator. The second-order rate constant for the reaction of the sulfate radical with N,N-diethyl-m-toluamide was found to be (1.9 ± 0.1) × 109 M?1 s?1 at pH 7 and a temperature of 25 °C. Experiments for the chemical oxidation of N,N-diethyl-m-toluamide in river water and secondary wastewater revealed that the percentage of the removal of N,N-diethyl-m-toluamide was slightly influenced by the water matrices. However, the selected oxidation systems are not effective for the removal of N,N-diethyl-m-toluamide in seawater. Transformation by-products of N,N-diethyl-m-toluamide generated using peroxymonosulfate/iron(II) sulfate, peroxymonosulfate/iron(II) chloride, peroxymonosulfate/cobalt(II) sulfate and peroxymonosulfate/cobalt(II) chloride systems were identified. The results indicated that there are slight differences in the distributions of the transformation by-products detected depending on the activator. The common transformation by-products detected in all selected oxidation systems are N,N-diethylbenzamide, N-ethyl-m-toluamide, N,N-dimethyl-m-toluamide, N-ethyl-N-acetyl-m-toluamide, 2-(diethylamino)-1-m-tolylethanone, monohydroxylated N-ethyl-m-toluamide, and dihydroxylated N,N-diethyl-m-toluamide. Monohydroxylated N,N-diethyl-m-toluamide were detected only when the peroxymonosulfate/iron(II) system was applied. For the peroxymonosulfate/cobalt(II) systems, additional isomers of monohydroxylated N-ethyl-m-toluamide were detected. Peroxymonosulfate/cobalt(II) also transformed 2-(diethylamino)-1-m-tolylethanone into N-ethyl-N-(2-oxo-2-m-tolylethyl)acetamide and monohydroxylated 2-(ethyl(vinyl)amino)-1-m-tolylethanone as transformation by-products. 相似文献
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Nasr Yousef M. J. Omar M. Radzi Bin Abas Noorsaadah A. Rahman Norhayati Mohd. Tahir Ahmed I. Rushdi Bernd R. T. Simoneit 《Environmental Geology》2007,52(8):1485-1500
The concentrations of n-alkanes, unresolved complex mixture (UCM), petroleum molecular markers, other tracers of cooking and burning emissions, and
natural background in atmospheric particles and roadside dust particles were measured at eight locations in the city center
and the suburbs of Kuala Lumpur, Malaysia. Atmospheric particles were collected using high-volume filtration (PM-10, GFF)
over 24 h average periods. Road dusts were swept up, dried and sieved. Both types of samples were extracted with dichloromethane/methanol
mixture (3:1 v/v) by ultrasonic agitation. The extracts were then fractionated by column chromatography and the alkanes subjected
to gas chromatography–mass spectrometry (GC–MS). Total extracts were also analyzed directly by GC–MS after silylation. The
molecular distributions of compounds as well as diagnostic geochemical ratios were determined in order to identify the sources
of the organic compounds. Samples collected from a rural area and lubricating oils were also analyzed for comparisons. Anthropogenic
and biogenic sources such as vehicular emissions, waxes of higher plants, food cooking operations, and biomass and domestic
refuse burning processes contributed to the organic matter content of atmospheric and to lesser extent, roadside dust particles. 相似文献
10.
Statistical analyses of the Karun III reservoir seismicity reveal a remarkable correlation between seismicity rate and water-level
harmonic changes. It seems that seismicity in this dam depends on rapid water-level changes. The three biggest earthquakes
of Karun III, measuring 4, 4.1, and 4.3 on the Richter scale (ML), occurred after two stages of rapid filling of the dam on
March 22, 2005 and May 12, 2006. These earthquakes happened when the water reached the maximum operational level. Since the
beginning of filling the reservoir on November 8, 2004 until March, 2006, most reservoir-induced seismicity has been localized
in three main clusters. The majority of the earthquakes occurred in the frontal anticline of Keyf Malek; the second and third
clusters happened near Karun Blind Fault (KBF) and Mountain Front Fault (MFF), respectively. Filling Karun III reservoir immediately
led to an increase in the occurrence of earthquakes. Further, following abrupt water-level changes, a considerable increase
in the number of earthquakes is observed. Finally, in terms of seismicity rate, vertical and horizontal migration, magnitude,
and distance, the earthquakes of Karun III behave differently. 相似文献