Design of small GPS drifters for current measurements in the coastal zone     

Behnam Shafiei Sabet  Gholam Abbas Barani 《Ocean & Coastal Management》2011,54(2):158-163

Field observations of flows in coastal zone are scarce, but important for understanding the spatial variability of currents. The design of small, low-cost GPS drifters for collecting accurate Lagrangian data in the coastal zone is described. The drifters are intended for using in nearshore environments, lakes and estuaries over timescales of a few minutes up to several hours and are a low-cost alternative for applications which do not require drifter’s sea-going capability. Two field tests of GPS drifters in the south coast of Caspian Sea in Anzali port, Iran, in November 2008 and July 2009 were successful.  相似文献   

The environmental dependence of galaxy clustering in the Sloan Digital Sky Survey     

Ummi Abbas  Ravi K. Sheth 《Monthly notices of the Royal Astronomical Society》2006,372(4):1749-1754

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Effects of Replacing Fishmeal with Animal By-products Meal Supplementation in Diets on the Growth and Nutrient Utilization of Mangrove Red Snapper   总被引：1，自引：0，他引：1  

Khalid Jamil Ghulam Abbas Rukhsana Akhtar LIN Hong LI Zhenxing 《中国海洋大学学报(英文版)》2007,6(3):292-298

A feeding trial was conducted for 75 d to evaluate the nutritive value of a mixture of animal by-products(MAB) as a possible protein source in diets for juvenile mangrove red snapper,Lutjanus argentimaculatus(mean initial body weight,30 g). Fish were fed one of five isonitrogenous diets(40% crude protein) replacing 0,25%(MAB25),50%(MAB50),75%(MAB75) and 100%(MAB100) of fish meal protein with similar percentages of MAB. The MAB consisted of 25% cow liver meal,20% leather meal,20% meat and bone meal,15% blood meal,10% APC(poultry feather meal),8% poultry manure dried,1.5% choline and 0.5% chromic oxide. After 75 d of feeding,fish fed with diets MAB50,MAB75 and MAB100 exhibited significantly lower growth per-formance than that of fish fed with control and MAB25 diets. The optimum level of MAB was estimated to be 23%. Replacement of fish meal by MAB23% showed the following performance:maximum weight gain,510%;SGR,2.39% and FCE,2.83%. The MAB substitution up to 75% of fish meal protein in diets did not show differences in apparent protein digestibility(83.6% for MAB25,79.2% for MAB50,78.7% for MAB75) compared with control(83.4%),whereas in MAB100 group digestibility(65.3%) was sig-nificantly lower than in other groups. The apparent phosphorus absorption of test diet groups was significantly higher(37.1% for MAB25,28.5% for MAB50,55.6% for MAB75 and 54.5% for MAB100) than that of control(11.2%). The levels of protein and ash in the whole body,carcass and viscera increased as MAB substitution in diets increased,whereas lipids and moisture remained con-sistent among all treatment groups. These results showed that approximately 23% of fish meal protein could be replaced by a mixture of animal by-products for juvenile snapper growing from 30 g to 167 g in 75 d without compromising growth performance and feed efficiency.  相似文献   

An Empirical Model for Significant Duration of the Ground Motions Containing Velocity Pulses     

Daryoushi  Masoud  Saffari  Hamid  Mahdavian  Abbas 《Izvestiya Physics of the Solid Earth》2021,57(6):950-964

Izvestiya, Physics of the Solid Earth - ln this study, two relationships have been presented for predicting the significant duration values $$({{D}_{{s5 - 75}}}$$ and $${{D}_{{s5 - 95}}})~$$ of...  相似文献   

A framework for predicting abrasion rupture of crusts in wind erosion     

Seyed Mohammad Fattahi  Abbas Soroush  Ning Huang  Jie Zhang  Sona Jodari Abbasi  Yang Yu 《地球表面变化过程与地形》2021,46(13):2565-2581

Crusts play a crucial role in the reduction or control of wind erosion. In this regard, the resilience and durability of crusts are of prime importance. Crusts have high resilience and durability against wind flow shear stresses; however, they are prone to abrasion induced by saltating particles. Therefore, estimating crust durability in abrasion rupture has practical importance. In this study, a cyanocrust and a biocemented sand crust were subjected to a controlled flux of saltating particles for different sandblasting periods to provide a framework for predicting crust rupture. The velocity and pre- and post-collision energy of the saltating particles were measured using high-speed photography. The changes in the strength of the crusts after different periods of sandblasting were determined using a scratch test. The results suggested that the average strength of the cyanocrust and biocemented sand crust became 0.25 and 0.7 of their corresponding initial values after 30 min of sandblasting. Also, the average stiffness of the cyanocrust and biocemented sand crust decreased to 0.5 and 0.9 of their initial values, respectively. Furthermore, the amount of impact energy absorbed by the crusts increased by the deterioration of the crusts. Compiling the results of the wind tunnel experiment and scratch tests yielded an exponential equation which can be used to estimate crust durability in a given condition of saltation. Based on this equation, the cyanocrust and biocemented sand crust will break down entirely after 23 and 449 min, respectively, at a wind velocity of 6.8 m/s and a saltation flux of 1 g/s/m.  相似文献   

Impacts of human activities and natural inputs on heavy metal contents of many coral reef environments along the Egyptian Red Sea coast     

Hashem Abbas Madkour 《Arabian Journal of Geosciences》2013,6(6):1739-1752

In order to monitor the heavy metals effect coming from both human activities and natural inputs on coral reef environments of the Egyptian Red Sea coast, metal concentrations in thirty- eight coral reef species and nearby sediment samples collected from seven studied sites were analyzed. Four sites represent impacted areas; included from south to north Hamrawein, Safaga and Hurghada Harbours and Ras El-Behar Area. Wadi El-Gemal represents natural input area while Qola'an and Kalawye Reefs are the control areas. Heavy metal contents were measured in both coral skeletons and nearby marine sediments. Both impact areas as well as natural inputs area recorded the highest values of metals compared with the control ones. However, heavy metal contents recorded high values in sediments of Hamrawein Harbour, while coral species recorded high values in Wadi El-Gemal area. Generally, metal variations in coral reef species reflect natural conditions and human activity. On the other hand, there are no clear relationships between concentrations of heavy metals in coral reef species and those in sediments.  相似文献   

Deforestation Trends and Spatial Modelling of its Drivers in the Dry Temperate Forests of Northern Pakistan–A Case Study of Chitral   总被引：2，自引：2，他引：0  

Khuram Shehzad  Faisal M. Qamer  M. S. R. Murthy  Sawaid Abbas  Laxmi D. Bhatta 《山地科学学报》2014,11(5):1192-1207

Deforestation is a major environmental challenge in the mountain areas of Pakistan. The study assessed trends in the forest cover in Chitral tehsil over the last two decades using supervised land cover classification of Landsat TM satellite images from 1992, 2000, and 2009, with a maximum likelihood algorithm. In 2009, the forest cover was 10.3% of the land area of Chitral(60,000 ha). The deforestation rate increased from 0.14% per annum in 1992–2000 to 0.54% per annum in 2000–2009, with 3,759 ha forest lost over the 17 years. The spatial drivers of deforestation were investigated using a cellular automaton modelling technique to project future forest conditions. Accessibility(elevation, slope), population density, distance to settlements, and distance to administrative boundary were strongly associated with neighbourhood deforestation. A model projection showed a further loss of 23% of existing forest in Chitral tehsil by 2030, and degradation of 8%, if deforestation continues at the present rate. Arandu Union Council, with 2212 households, will lose 85% of its forest. Local communities have limited income resources and high poverty and are heavily dependent on non-timber forest products for their livelihoods. Continued deforestation will further worsen their livelihood conditions, thus improved conservation efforts are essential.  相似文献   

Integrated risk assessment of urban water supply systems from source to tap   总被引：1，自引：1，他引：0  

Abbas Roozbahani  Banafsheh Zahraie  Massoud Tabesh 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(4):923-944

Urban water supply systems (UWSS) are generally composed of water sources, transmission pipes, treatment plants, and distribution networks from source to tap and usually are exposed to variety of uncertain threatening hazards. These threats can be divided to three main groups of natural, human-made, and operational hazards which affect either water quantity or water quality. In order to evaluate the reliability of water supply systems, risk assessment tools must be used to identify threats, their probability, and consequences and vulnerabilities of each element of these systems against the hazards. Due to the complexity and uncertainties affecting water supply systems and threatening hazards, a comprehensive and effective risk assessment method is required. In this study, an integrated fuzzy hierarchical risk assessment model for water supply systems (IFHRA-WSS) is proposed to assess hazards in a complex UWSS using a systematic approach incorporating both water quantity and quality issues. This model uses a hierarchical framework for breaking down the UWSS infrastructures to their interrelated elements to reduce the overall complexity of the system. It also considers uncertainties using Fuzzy Logic approach. Effects of functional interdependencies between different components of the system have also been considered in the vulnerability analysis. IFHRA-WSS incorporates the contributions of urban water experts in a group risk assessment procedure in a way that they can be easily expressed in terms of the qualitative and quantitative risk measures. Efficiency of this model has been examined in a case study which includes a large part of a drinking water supply system in a major city in Iran. This system includes all the elements of the UWSS from the delivery point to the consumption point. In the case study, different components and subcomponents of this system have been ranked based on their estimated risk values. It is envisaged that the results of the proposed model can help the decision makers to plan for effective risk mitigation measures.  相似文献   

Robustness and uncertainties of seismic damage estimates at urban scale: a methodological comparison on the example of the city of Oran (Algeria)     

Abbas Senouci  Pierre Yves Bard  Mohamed Naboussi Farsi  Elise Beck  Stéphane Cartier 《Bulletin of Earthquake Engineering》2013,11(4):1191-1215

The city of Oran is exposed to a significant seismic hazard, as almost all the northern Algeria territory, where numerous casualties and severe damage occurred in the last decades due to several moderate to large earthquakes. A mitigation policy should include the establishment of priorities to reduce the vulnerability of existing buildings based on the knowledge of the actual urban fabrics. The complexity of vulnerability assessment requires a gradual approach from the urban scale to the building scale. The study reported in this paper corresponds to the first step of such an approach, i.e., a preliminary study of the seismic vulnerability and expected damage within an urban district of the city of Oran, based on a non-dedicated data base from a building survey previously performed for other purposes. The main goals of this study are twofold: (1) an assessment of the degree of uncertainty and robustness of such results through a comparison of the results derived from different urban vulnerability methods (GNDT 2; RISK-UE LM1; and VULNERALP 2.0) and (2) an assessment of the actual level of seismic risk in the city of Oran. Cross-method comparisons and correlations highlight a satisfactory agreement between mean damage estimates at the urban scale, despite significant scattering at the single building scale, and uncertainty levels which vary significantly from one method to the other. For a given scenario, the three methods provide damage estimates lying within half an EMS damage degree of one another, with some systematic positive bias for VULNERALP and negative bias for RISK-UE LM1, especially for masonry buildings. The expected mean damage is very important for intensities 9 and 10, with an average damage grade around 3–4 for intensity 9 and 4–5 for intensity 10. The spatial distribution of damage systematically exhibits larger values in the northern, older, commercial area, than in the southern, more recent and more residential area, in relation to the building typology and the existence of several aggravating factors. Some areas of higher vulnerability / damage can be distinguished, which should receive particular attention for retrofitting priorities or urban planning decisions, also taking into account their cultural heritage value.  相似文献   

Environmental and Health Impacts of Successive Mineral Fertilization in Egypt     

Ahmed A. Abdelhafez  Hassan H. Abbas  Rafat S. Abd‐El‐Aal  Nabil F. Kandil  Jianhua Li  Wahballah Mahmoud 《洁净——土壤、空气、水》2012,40(4):356-363

Excessive amounts of mineral fertilizers are unnecessarily applied to agricultural soils in Egypt to increase crop yield. The current study aims at assessing the impacts of fertilization with different mineral fertilizers for different cultivation periods on the accumulation of heavy metals in soils and plants grown thereon. In addition, human risks resulted due to the exposure to these metal ions through ingestion, and dermal routes were evaluated. Soil and plant samples were collected from several locations in El‐Behira Governorate, Egypt and their heavy metal contents were measured. The result indicated that there is a continuous accumulation of heavy metals in the soils and the plants grown thereon. Calculation of the hazard index (HI) revealed that humans, especially children, have a potential health risk for both Pb and Cd, which have levels greater than the safe level (1). Finally, the obtained results showed that the continuous application of mineral fertilizers containing high levels of heavy metals pose a potential health threat.  相似文献