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21.
A. Abbasi A. Barkhordari S. Hekmatimoghaddam A. Jebali 《International Journal of Environmental Science and Technology》2017,14(1):95-100
Nanocomposites can be used as an acoustic panel to adsorb noise. The aim of this study was to evaluate: (1) acoustic, (2) physical, and (3) mechanical properties of agro-environmental nanocomposites. To prepare the nanocomposites, wood flour, PVA glue, and aluminum nanoparticles (between 1 and 4 %) were hardly mixed and heated at near 220 °C for 120 min. In the next step, sound absorption coefficient, transmission loss, water absorption percentage, thickness swelling percentage, density, flexural strength, flexural modulus, tensile strength, and tensile modulus of nanocomposites were measured. This study showed that the increase in nanoparticle percentage led to the increase in flexural strength, flexural modulus, water absorption percentage, thickness swelling percentage, density, and sound absorption coefficient. But, the increase in nanoparticle percentage led to the decrease in tensile strength, tensile modulus, and transmission loss. The authors think that the nanocomposites are suitable as an agro-industrial nanocomposite to reduce noise. 相似文献
22.
Pre-seismic, co-seismic and post-seismic displacements associated with the Bhuj 2001 earthquake derived from recent and historic geodetic data 总被引：1，自引：0，他引：1
Sridevi Jade M. Mukul I. A. Parvez M. B. Ananda P. D. Kumar V. K. Gaur R. Bendick R. Bilham F. Blume K. Wallace I. A. Abbasi M. Asif Khan S. Ulhadi 《Journal of Earth System Science》2003,112(3):331-345
The 26th January 2001 Bhuj earthquake occurred in the Kachchh Rift Basin which has a long history of major earthquakes. Great
Triangulation Survey points (GTS) were first installed in the area in 1856–60 and some of these were measured using Global
Positioning System (GPS) in the months of February and July 2001. Despite uncertainties associated with repairs and possible
reconstruction of points in the past century, the re-measurements reveal pre-seismic, co-seismic and post-seismic deformation
related to Bhuj earthquake. More than 25 Μ-strain contraction north of the epicenter appears to have occurred in the past
140 years corresponding to a linear convergence rate of approximately 10 mm/yr across the Rann of Kachchh. Motion of a single
point at Jamnagar 150 km south of the epicenter in the 4 years prior to the earthquake, and GTS-GPS displacements in Kathiawar
suggests that pre-seismic strain south of the epicenter was small and differs insignificantly from that measured elsewhere
in India. Of the 20 points measured within 150 km of the epicenter, 12 were made at existing GTS points which revealed epicentral
displacements of up to 1 m, and strain changes exceeding 30 Μ-strain. Observed displacements are consistent with reverse co-seismic
slip. Re-measurements in July 2001 of one GTS point (Hathria) and eight new points established in February reveal post-seismic
deformation consistent with continued slip on the Bhuj rupture zone. 相似文献
23.
The concentration of trace elements in the groundwater of the Ganga–Nim basin was ascertained. It was found that Zn, Cu, Cd, and Mn are below the permissible limits. Fe and Pb are above the permissible limits. 相似文献
24.
This paper deals with the basic definitions and the numerical techniques used nowaday in the estimation of the gradiometric geoid. After a first introductory paragraph, the so-called 3-steps remove/restore method is presented. The computation and the use of global models is analysed in Section 2; the computation of topographic corrections, with particular care to the residual terrain correction, is presented in Section 3; the central solution or estimation of the anomalous potential either by solving a Molodensky's problem, or by applying the collocation theory, is examined in Section 4; the restore step is finally presented in Section 5. 相似文献
25.
Atmospheric stability conditions over the water surface can affect the evaporative and convective heat fluxes from the water surface. Atmospheric instability occurred 72.5% of the time and resulted in 44.7 and 89.2% increases in the average and maximum estimated evaporation, respectively, when compared to the neutral condition for a small shallow lake (Binaba) in Ghana. The proposed approach is based on the bulk-aerodynamic transfer method and the Monin-Obukhov similarity theory (MOST) using standard meteorological parameters measured over the surrounding land. For water surface temperature, a crucial parameter in heat flux estimation from water surfaces, an applicable method is proposed. This method was used to compute heat fluxes and compare them with observed heat fluxes. The heat flux model was validated using sensible heat fluxes measured with a 3-D sonic anemometer. The results show that an unstable atmospheric condition has a significant effect in enhancing evaporation alongside the sensible heat flux from water surfaces. 相似文献
26.
Assessment and Modification of Sherard Chemical Method for Evaluation of Dispersion Potential of Soils 总被引：1，自引：1，他引：0
Soil dispersion is a phenomenon in which soil particles become afloat when they are exposed to water, and are carried away by the force of seepage. In spite of that soil dispersion is due to its chemical composition, the results obtained from the chemical methods, especially from the most widely used, Sherard method does not match with the results of well-known Pinhole test. This study tries to evaluate and modify the Sherard diagram for determination of dispersion potential of clayey soils. For this purpose, several natural soil samples were collected from different regions of Iran and some artificial soil samples were made by adding different percentages of four chemical agents, including sodium chloride, sodium carbonate, sodium sulfate, and sodium polyphosphate to a natural soil. The physical, chemical and index properties of all samples were determined and for determination of dispersion potential, the commonly used chemical test (Sherard method) and Pinhole test were employed. The results obtained from the tests showed that the Sherard chemical method which is solely based on the amount and type of the existing cations, is not able to determine soil dispersion correctly since the role of some anions, especially chloride is neglected. It was also found that among the existing anions in the soil, the chloride on the contrary to sodium acts as a flocculating factor. The results showed that by converting the vertical axis of the Sherard chart from sodium% to (sodium chloride)%, its conformity to the results of Pinhole tests increases considerably. 相似文献
27.
Alireza Abbasi 《Natural Hazards》2014,71(3):1957-1969
This study aims to understand the mechanisms of emergency response network evolution by quantitatively examining the link formation pattern among participants involved in a real emergency collaboration network. This is achieved by identifying the participants’ characteristics which can affect forming new links over time. The result indicates the existence of cumulative advantage process, where highly connected participants gain more new links over time. It also reveals the structural position of participants involved in a response network, i.e. brokering position, affects their number of future links. Understanding the link formation pattern is important for understanding the mechanisms of network evolution which help predict more precisely the behavior of actors and dynamics of network structure over time. This can assist researchers, decision makers and practitioners to manage and support the collaboration of actors in their systems in order to reach their organizational goals. The overall findings can contribute further to the development of network organizational theory in different contexts especially disaster and emergency response management. 相似文献
28.
Iftikhar Ahmed Abbasi Osman Salad Hersi Abdulrahman Al-Harthy Iman Al-Rashdi 《Arabian Journal of Geosciences》2013,6(12):4931-4945
Over 70 m thick interbedded sandstone, siltstone and claystone of the upper member of the Gharif Formation are exposed in western Huqf area in Oman Interior Sedimentary Basin. The Gharif Formation, particularly its upper member hosts major hydrocarbon reservoir in the subsurface of the Oman Interior Sedimentary Basin. The upper member of the Gharif Formation is comprised of interbedded thick sandstone, siltstone, carbonaceous clays and intraformational conglomerates. The sandstone lithofacies, on average, constitute 10 m thick multistoreyed sequences, which are composed internally of 2–3 m thick and 100 s of metres across vertically and laterally amalgamated sandstone bodies. Two major types of sandstones (types 1 and 2) are identified on the basis of their lithofacies association and internal architecture. The type 1 sandstone constitutes the lower part of the member and is comprised of pebbly to coarse-grained, planar and trough cross-bedded sandstone, plane bedded sandstone and pebble lags at the base of major sandstone bodies. The cross-beds are, on average, 30 cm thick exhibiting a dominant paleoflow direction towards NW (280–300° N). It is interpreted to be deposited by low sinuosity braided streams. The type 2 sandstone constitutes the upper part of the member and is comprised of medium-grained sandstone, trough to low angle plane bedding associated with lateral accretion surfaces. It is commonly interbedded with carbonaceous clays. Silicified plant fragments are commonly distributed in the upper part of the sandstone. Interbedded clays and siltstones are red, mottled and extensively bioturbated due to root burrows. It is interpreted to be deposited by high sinuosity meandering streams. In the uppermost part of the section, several dark grey to black carbonaceous clay/coal beds with plant matter are interbedded with sandstone and red clay indicating development of swampy conditions during onset of the coastal setting in the uppermost part of the formation. About 30 cm thick bioclastic sandstone deposited by the marine coastal bars mark transition from the Gharif Formation to carbonate dominated Khuff Formation. The sandstone of the Gharif Formation is arkosic in composition. Very small amount of cement and negligible compaction of constituent grains in sandstone indicates shallow burial before uplift. 相似文献
29.
Sajjad Abbasi Behnam Keshavarzi Farid Moore Hossein Delshab Naghmeh Soltani Armin Sorooshian 《Environmental Earth Sciences》2017,76(23):798
This study aimed to (1) investigate microrubbers (MRs) for the first time and identify microplastics (MPs) in street dust, (2) determine the physicochemical and mineralogical characteristics and morphology of dust particles, (3) understand the concentration and the possible source(s) of heavy metals/metalloids, (4) identify the chemical speciation and mobility potential of trace metals in urban street dusts, and (5) determine adverse health effects of street dust on children and adults living in the city of Bushehr in southwestern Iran. Generally, twenty four street dust samples were collected and analyzed. Calculated enrichment factors indicate high levels of contamination. Statistical analysis reveals that the two main sources of trace elements include road traffic emissions (Cu, Zn, Sb, Hg, Pb, Mo) and re-suspended soil particles (Al, Mn, Ni, Ti, Cd, Co). BCR sequential extraction results indicated that As, Zn, Cu, and Pb mainly occur in the exchangeable fraction and hence are highly bioavailable. X-ray powder diffraction analysis revealed the presence of calcite, dolomite, quartz, and magnetite. The size distribution of dust particles was also investigated using a scanning electron microscope (SEM), while elemental distribution was analyzed using an attached energy dispersive X-ray spectrometer (SEM–EDS) unit. Dust particles from heavy traffic areas are much finer compared with other investigated areas. MPs and MRs, mostly fibers and fragments, were detected in all samples [ranging from 210 to 1658 (MPs) and 44 to 782 (MRs) items/10 g dust] using fluorescence microscopy. The hazard index for As is higher than 10?4 for children and adults indicative of high risk. According to the calculated potential ecological risk index, Hg indicated moderate ecological risk in the street dust of the study area. 相似文献
30.
Airborne LaCoste &; Romberg gravimetry: a space domain approach 总被引：1，自引：0，他引：1
This paper introduces a new approach to reduce the airborne gravity data acquired by a LaCoste &; Romberg (L&;R) air/sea gravimeter, or other similar gravimeters. The acceleration exerted on the gravimeter is the sum of gravity and the vertical and Eötvös accelerations of the aircraft. The L&;R gravimeter outputs are: (1) the beam position, (2) the spring tension and (3) the cross coupling. Vertical and Eötvös accelerations are computed from GPS-derived aircraft positions. However, the vertical perturbing acceleration sensed by the gravimeter is not the same as the one sensed by the aircraft (via GPS). A determination of the aircraft-to-sensor transfer function is necessary. The second-order differential equation of the motion of the gravimeter’s beam mixes all the input and output parameters of the gravimeter. Conventionally, low-pass filtering in the frequency domain is used to extract the gravity signal, the filter being applied to each flight-line individually. By transforming the differential equation into an integral equation and by introducing related covariance matrices, we develop a new filtering method based on a least-squares approach that is able to take into account, in one stage, the data corresponding to all flight-lines. The a posteriori covariance matrix of the estimated gravity signal is an internal criterion of the precision of the method. As an example, we estimate the gravity values along the flight-lines from an airborne gravity survey over the Alps and introduce an a priori covariance matrix of the gravity disturbances from a global geopotential model. This matrix is used to regularize the ill-posed Fredholm integral equation introduced in this paper. 相似文献