Open Science Research Excellence

R Jafari

Publications

10

Publications

10
2187
Using Environmental Sensitivity Index (ESI) to Assess and Manage Environmental Risks of Pipelines in GIS Environment: A Case Study ofa Near Coastline and Fragile Ecosystem Located Pipeline
Abstract:
Having a very many number of pipelines all over the country, Iran is one of the countries consists of various ecosystems with variable degrees of fragility and robusticity as well as geographical conditions. This study presents a state-of-the-art method to estimate environmental risks of pipelines by recommending rational equations including FES, URAS, SRS, RRS, DRS, LURS and IRS as well as FRS to calculate the risks. This study was carried out by a relative semi-quantitative approach based on land uses and HVAs (High-Value Areas). GIS as a tool was used to create proper maps regarding the environmental risks, land uses and distances. The main logic for using the formulas was the distance-based approaches and ESI as well as intersections. Summarizing the results of the study, a risk geographical map based on the ESIs and final risk score (FRS) was created. The study results showed that the most sensitive and so of high risk area would be an area comprising of mangrove forests located in the pipeline neighborhood. Also, salty lands were the most robust land use units in the case of pipeline failure circumstances. Besides, using a state-of-the-art method, it showed that mapping the risks of pipelines out with the applied method is of more reliability and convenience as well as relative comprehensiveness in comparison to present non-holistic methods for assessing the environmental risks of pipelines. The focus of the present study is “assessment" than that of “management". It is suggested that new policies are to be implemented to reduce the negative effects of the pipeline that has not yet been constructed completely
Keywords:
ERM, ESI, ERA, Pipeline, Assalouyeh
9
6712
On the Oil Repellency of Nanotextured Aluminum Surface
Abstract:
Two different superhydrophobic surfaces were elaborated and their oil repellency behavior was evaluated using several liquid with different surface tension. A silicone rubber/SiO2 nanocomposite coated (A) on aluminum substrate by “spin-coating" and the sample B was an anodized aluminum surface covered by Teflon-like coating. A high static contact angle about ∼162° was measured for two prepared surfaces on which the water droplet rolloff. Scanning electron microscopy (SEM) showed the presence of micro/nanostructures for both sample A and B similar to that of lotus leaf. However the sample A presented significantly different behaviour of wettability against the low surface tension liquid. Sample A has been wetted totally by oil (dodecan) droplet while sample B showed oleophobic behaviour. Oleophobic property of Teflon like coating can be contributed to the presence of CF2 and CF3 functional group which was shown by XPS analysis.
Keywords:
Oleophobic, Superhydrophobic, Aluminum surface, Nano-texture.
8
10309
Hydrothermal Alteration Zones Identification Based on Remote Sensing Data in the Mahin Area, West of Qazvin Province, Iran
Abstract:
The Mahin area is a part of Tarom- Hashtjin zone that located in west of Qazvin province in northwest of Iran. Many copper and base metals ore deposits are hosted by this zone. High potential localities identification in this area is very necessary. The objective of this research, is finding hydrothermal alteration zones by remote sensing methods and best processing technique of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data. Different methods such as band ratio, Principal Component Analysis (PCA), Minimum Noise Fraction (MNF) and Least Square Fit (LS-Fit) were used for mapping hydrothermal alteration zones.
Keywords:
Hydrothermal alteration, Iran, Mahin, Remote sensing
7
10776
Determination of Cu and Mo Potential Targets in the Khatunabad Based on Analytical Hierarchy Process, West of Mianeh, Iran
Abstract:
Khatunabad area is situated geologically in Urmieh- Dokhtar magmatic belt in NW of Iran. In this research, studied area has been investigated in order to recognize the potential copper and molybdenum-bearing target areas. The survey layers include the lithologic units, alteration, geochemical result, tectonics and copper and molybdenum occurrence. As an accurate decision can have a considerable effect on exploration plans, so in this efforts have been made to make use of new combination method. For this purpose, the analytical hierarchy process was used and revealed highly potential copper and molybdenum mineralization areas. Based on achieved results, geological perspective in north of studied area is appropriate for advance stage, especially for subsurface exploration in future.
Keywords:
Analytical hierarchy process, Potential targets,Khatunabad, Iran
6
14341
P-ACO Approach to Assignment Problem in FMSs
Abstract:

One of the most important problems in production planning of flexible manufacturing system (FMS) is machine tool selection and operation allocation problem that directly influences the production costs and times .In this paper minimizing machining cost, set-up cost and material handling cost as a multi-objective problem in flexible manufacturing systems environment are considered. We present a 0-1 integer linear programming model for the multiobjective machine tool selection and operation allocation problem and due to the large scale nature of the problem, solving the problem to obtain optimal solution in a reasonable time is infeasible, Paretoant colony optimization (P-ACO) approach for solving the multiobjective problem in reasonable time is developed. Experimental results indicate effectiveness of the proposed algorithm for solving the problem.

Keywords:
Flexible manufacturing system, Production planning, Machine tool selection, Operation allocation, Multiobjective optimization, Metaheuristic.
5
10005691
Experimental and Finite Element Study of Bending Fatigue Failure: A Case Study on Main Shaft of a Gyrator Crusher
Abstract:

This study investigates the mechanism of a Gyratory crusher-located in Golgohar mining and industrial Co. specifically with a focus on stresses distribution and fatigue failure of its main shaft. At first step, the cross section of the fractured shaft is studied, and the crack growth is analyzed. Then, the rotational motion of the shaft and the oil temperature of oil circuit of equipment are monitored. Condition monitoring is used to help finding a better modification. Based on the results of this study, the main causes of shaft failure are identified, and corrective solution is offered to increase crusher performance, especially its main shaft life. To predict the efficiency of the proposed modification, finite element simulation is performed, and its results are compared with the similar modified cases. The comparison and interpretation of simulation results confirm the efficiency of proposed corrective method.

Keywords:
Fatigue failure, finite element method, gyratory crusher, condition monitoring.
4
10005820
Constitutive Modeling of Different Types of Concrete under Uniaxial Compression
Abstract:
The cost of experiments on different types of concrete has raised the demand for prediction of their behavior with numerical analysis. In this research, an advanced numerical model has been presented to predict the complete elastic-plastic behavior of polymer concrete (PC), high-strength concrete (HSC), high performance concrete (HPC) along with different steel fiber contents under uniaxial compression. The accuracy of the numerical response was satisfactory as compared to other conventional simple models such as Mohr-Coulomb and Drucker-Prager. In order to predict the complete elastic-plastic behavior of specimens including softening behavior, disturbed state concept (DSC) was implemented by nonlinear finite element analysis (NFEA) and hierarchical single surface (HISS) failure criterion, which is a failure surface without any singularity.
Keywords:
Disturbed state concept, hierarchical single surface, failure criterion, high performance concrete, high-strength concrete, nonlinear finite element analysis, polymer concrete, steel fibers, uniaxial compression test.
3
10006142
Steering Velocity Bounded Mobile Robots in Environments with Partially Known Obstacles
Abstract:
This paper presents a method for steering velocity bounded mobile robots in environments with partially known stationary obstacles. The exact location of obstacles is unknown and only a probability distribution associated with the location of the obstacles is known. Kinematic model of a 2-wheeled differential drive robot is used as the model of mobile robot. The presented control strategy uses the Artificial Potential Field (APF) method for devising a desired direction of movement for the robot at each instant of time while the Constrained Directions Control (CDC) uses the generated direction to produce the control signals required for steering the robot. The location of each obstacle is considered to be the mean value of the 2D probability distribution and similarly, the magnitude of the electric charge in the APF is set as the trace of covariance matrix of the location probability distribution. The method not only captures the challenges of planning the path (i.e. probabilistic nature of the location of unknown obstacles), but it also addresses the output saturation which is considered to be an important issue from the control perspective. Moreover, velocity of the robot can be controlled during the steering. For example, the velocity of robot can be reduced in close vicinity of obstacles and target to ensure safety. Finally, the control strategy is simulated for different scenarios to show how the method can be put into practice.
Keywords:
Steering, obstacle avoidance, mobile robots, constrained directions control, artificial potential field.
2
10006155
Experimental Study of Different Types of Concrete in Uniaxial Compression Test
Abstract:

Polymer concrete (PC) is a distinct concrete with superior characteristics in comparison to ordinary cement concrete. It has become well-known for its applications in thin overlays, floors and precast components. In this investigation, the mechanical properties of PC with different epoxy resin contents, ordinary cement concrete (OCC) and lightweight concrete (LC) have been studied under uniaxial compression test. The study involves five types of concrete, with each type being tested four times. Their complete elastic-plastic behavior was compared with each other through the measurement of volumetric strain during the tests. According to the results, PC showed higher strength, ductility and energy absorption with respect to OCC and LC.

Keywords:
Polymer concrete, ordinary cement concrete, lightweight concrete, uniaxial compression test, volumetric strain.
1
10010348
Deep Injection Wells for Flood Prevention and Groundwater Management
Abstract:
With its arid climate, Qatar experiences low annual rainfall, intense storms, and high evaporation rates. However, the fast-paced rate of infrastructure development in the capital city of Doha has led to recurring instances of surface water flooding as well as rising groundwater levels. Public Work Authority (PWA/ASHGHAL) has implemented an approach to collect and discharge the flood water into a) positive gravity systems; b) Emergency Flooding Area (EFA) – Evaporation, Infiltration or Storage off-site using tankers; and c) Discharge to deep injection wells. As part of the flood prevention scheme, 21 deep injection wells have been constructed to discharge the collected surface and groundwater table in Doha city. These injection wells function as an alternative in localities that do not possess either positive gravity systems or downstream networks that can accommodate additional loads. These injection wells are 400-m deep and are constructed in a complex karstic subsurface condition with large cavities. The injection well system will discharge collected groundwater and storm surface runoff into the permeable Umm Er Radhuma Formation, which is an aquifer present throughout the Persian Gulf Region. The Umm Er Radhuma formation contains saline water that is not being used for water supply. The injection zone is separated by an impervious gypsum formation which acts as a barrier between upper and lower aquifer. State of the art drilling, grouting, and geophysical techniques have been implemented in construction of the wells to assure that the shallow aquifer would not be contaminated and impacted by injected water. Injection and pumping tests were performed to evaluate injection well functionality (injectability). The results of these tests indicated that majority of the wells can accept injection rate of 200 to 300 m3 /h (56 to 83 l/s) under gravity with average value of 250 m3 /h (70 l/s) compared to design value of 50 l/s. This paper presents design and construction process and issues associated with these injection wells, performing injection/pumping tests to determine capacity and effectiveness of the injection wells, the detailed design of collection system and conveying system into the injection wells, and the operation and maintenance process. This system is completed now and is under operation, and therefore, construction of injection wells is an effective option for flood control.
Keywords:
Deep injection well, wellhead assembly system, emergency flood area, flood prevention scheme, geophysical tests, pumping and injection tests, Qatar geology.