Ali Akbar Rahimi Bahar
Abstract
Accurate estimation of hydrocarbon volume in a reservoir is important due to future development and investment on that reservoir. Estimation of Oil and Gas reservoirs continues from exploration to end of reservoir time life and is usual upstream engineer’s involvements. In this study we tried to make ...
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Accurate estimation of hydrocarbon volume in a reservoir is important due to future development and investment on that reservoir. Estimation of Oil and Gas reservoirs continues from exploration to end of reservoir time life and is usual upstream engineer’s involvements. In this study we tried to make reservoir properties models (porosity and water saturation) and estimate reservoir volume hydrocarbon based on artificial neural network tools, petrophysical and geophysical data. So with gridding the reserve, separate it to same volume cells. Based on porosity and lithology variation in wells, constructed petrophysical zonation in each well and by correlation these zones in wells reservoir has been zoned. Porosity, water saturation and 3D seismic data have been averaged in cells and assigned one value for each cell. At final a three layer perceptron neural network by back propagation error algorithm has been designed and trained by using cells which had petrophysical data; then these parameters have been estimated in other cells and original hydrocarbon in place calculated and compared with results from Mont Carlo method.
Mohammad Tale'i; Mohammad Sa'di Mesgari; Ali Sharifi
Abstract
This research is aimed at developing a model for measuring and comparison amount of supply and demand for different urban services from quality of life and equity perspectives, in urban built-up areas. This paper explains different steps of implementing the model as a tool for evaluating accessibility ...
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This research is aimed at developing a model for measuring and comparison amount of supply and demand for different urban services from quality of life and equity perspectives, in urban built-up areas. This paper explains different steps of implementing the model as a tool for evaluating accessibility of residents to various services according to two main criteria: Land per capita and distance to services. In developing the model, geographic information system is used as a spatial planning support generator. The model has been tested in an urban area located in 7th regional municipality of Tehran, the capital city of Iran, and its result have been compared with outcomes of traditional techniques such as zoning. The results show that the model is effectively proper to clarify different levels of shortcoming in accessibility to urban land use services and improves accuracy of assessing the amount and location of the shortcomings. Developing such GIS-based micro-level evaluation model and presenting different approach regarding single-facility and multi-facility’s characteristics of urban services are the specific originality of this research.
Mohammad Reza Ghaemmaghamian; Behnam Khalili
Abstract
The characteristics of near-fault ground motion are investigated considering heterogeneous slip distribution on the fault plane. Areas on the fault plane with large slip in compare with the average slip on the fault are known as asperity. The characteristics of strong ground motions in near-fault area ...
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The characteristics of near-fault ground motion are investigated considering heterogeneous slip distribution on the fault plane. Areas on the fault plane with large slip in compare with the average slip on the fault are known as asperity. The characteristics of strong ground motions in near-fault area are strongly affected by faulting parameters such as asperity location, maximum slip of asperity, rise time and rupture velocity on the fault plane. Based on theoretical Green’s function for infinite media, the near-fault pulse is simulated for finite fault model with different faulting specifications. Then, the variations of each fault parameter and site to fault distance on near-fault pulse characteristics are numerically examined and discussed.
Ramezanali Mahdavi Nejad; Mohammad Gholami Nejad Saniabadi
Abstract
Dimensional accuracy in machined parts depends on the precision of spindle, which is highly affected by applied forces, itself. This precision of spindle becomes more serious when it is used for a period of long times. Therefore, stress and strain analysis of spindle is very important in the behavior ...
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Dimensional accuracy in machined parts depends on the precision of spindle, which is highly affected by applied forces, itself. This precision of spindle becomes more serious when it is used for a period of long times. Therefore, stress and strain analysis of spindle is very important in the behavior and preservation of its precision. In this paper, the forces applied to the spindle of a turning machine are calculated and analyzed. Afterwards, the spindle is simulated with MSC Visual Nastran software and analyzed due to the application of boundary conditions. According to the spindle’s stress and strain, the modal analysis has been done and the natural frequencies of the spindle are determined. The results show that, the front bearing of the spindle is the critical section and its stress and strain will be increased with feed and depth of cut. When these feed rates and depths of cut become less, the created stresses at the least speed of spindle are more in comparison with the other speeds.
Ebrahim Azimi; Samad Banisi; Gholamreza Langarizadeh; Malek Dehghani
Abstract
Discharge grates are one of the most important parts of SAG mills. These grates prevent balls and unbroken ores from discharging the mill and they have a significant effect on the mill filling and size distribution of the discharge flow. To consider the effect of openings of the grates on the overall ...
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Discharge grates are one of the most important parts of SAG mills. These grates prevent balls and unbroken ores from discharging the mill and they have a significant effect on the mill filling and size distribution of the discharge flow. To consider the effect of openings of the grates on the overall efficiency of the comminution operation, the variation of the grates shape and size were closely monitored for a period of 5600 hours at the Sarcheshmeh copper concentration plant. Using measured values the changes in the amount of open area, the thickness of grates plates, the width of grates openings with respect to their radial position and grate plugging were determined. The results indicated that 1% increase in open area causes 0.4% increase in the circulating load of the circuit. The useful operational time of the grates was found to be 5000 hours beyond which the efficiency decreases.
Seyyed Mohammad Azimi; Sa'eed Afsharnia
Javad Rasti; Seyyed Amir Monajjemi; Abbas Vafaei
Abstract
Reducing the number of colors in an image while preserving its quality, is of importance in many applications such as image analysis and compression. It also decreases memory and transmission bandwidth requirements. Moreover, classification of image colors is applicable in image segmentation and object ...
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Reducing the number of colors in an image while preserving its quality, is of importance in many applications such as image analysis and compression. It also decreases memory and transmission bandwidth requirements. Moreover, classification of image colors is applicable in image segmentation and object detection and separation, as well as producing pseudo-color images. In this paper, the Kohenen Self-Organizing Map Neural Network is employed to form an adaptive color reduction method. To enhance the performance of this method, we have used redundant features obtained by one-to-one functions from three main components of the color image (e.g. Red, Green and Blue channels). Exploiting these features will increase the color discrimination and details illustration ability of the network compared to the conventional approaches. This method leads to satisfactory results in image segmentation and especially in small object detection problems. It is also investigated that if the number of features in Kohenen network grows even by using non-deterministic one-to-one functions, the network revenue considerably improves. Moreover, we will study the effect of various adaptation algorithms in Kohenen network training stage. Again using a multi-stage color reduction procedure which employs both Kohenen neural networks and conventional vector quantization schemes improves the performance. Several experimental results are represented to simplify the comparison of different approaches.
Masoud Tabesh; Arash Aghaei; Jalil Abrishami
Abstract
A water distribution network is one of the important parts of infrastructure systems. The efficient management and proactive planning of capital investment of these assets are fundamental for efficient and effective service delivered by water companies. The direct economic costs (i.e. rehabilitation ...
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A water distribution network is one of the important parts of infrastructure systems. The efficient management and proactive planning of capital investment of these assets are fundamental for efficient and effective service delivered by water companies. The direct economic costs (i.e. rehabilitation investment, repair costs, water loss, etc.) as well as indirect costs (i.e. service and traffic interruptions, etc.) related to water pipe bursts are rapidly increasing. The ability to predict burst rate in pipes is an important strategic key in order to optimization of rehabilitation decision in water distribution systems. Most networks suffer from lack of enough and reliable data for bursts and failures. In this study basic variables which influence on pipes burst and burst statistical analysis have been identified and evaluated. Then common methods for burst predicting are discussed. In order to identify logical, useful and understandable patterns of breaks data, a data mining methodology named evolutionary polynomial regression (EPR) is described. Starting from a hybrid evolutionary strategy, EPR searches for patterns in data and returns symbolic expressions/models. This approach is demonstrated through a detailed case study. Required data were collected from the Mashhad Water Company which includes both asset and bursts data recorded for year 1384. The whole database was divided into 8 material/diameter classes (from 64 mm to 300 mm). The resulting models for burst prediction in different zones contain explicitly recognizable independent variables. The expression models confirm that pipe age, diameter and length are the most important variables leading to pipe bursts. Also the effects of pressure on pipe burst prediction were implicitly investigated. It was found that pressure is an important parameter which influences number of breaks in a pipe network.
Hamid Zaferani; Asadollah Noorzad; Khosro Bargi
Hirosh Seyyedi; Majid Sanaye Pasand
Abstract
In recent years several catastrophic power systems blackouts have occurred worldwide. Various reasons have been declared for these failures. Economical limitations due to power system restructuring restrictions, inadvertent operation of protective relays and inefficient design of conventional load shedding ...
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In recent years several catastrophic power systems blackouts have occurred worldwide. Various reasons have been declared for these failures. Economical limitations due to power system restructuring restrictions, inadvertent operation of protective relays and inefficient design of conventional load shedding schemes are of the most important reasons causing these blackouts. In fact, due to both economical and technological restrictions, it is not possible to completely prevent these blackouts. However, with the aid of some protection and control strategies, frequency and intensity of these blackouts may be reduced. One of the important protection strategies used for this purpose is a class of protection schemes known as ‘System Protection Schemes’ or ‘Wide Area Protection Schemes’. One of the most commonly used types of system protection schemes, generally accepted after the north-eastern blackout of 1965, is Under Frequency Load Shedding (UFLS) scheme. Conventional under frequency load shedding scheme is designed to retrieve the balance of generation and consumption following a disturbance. In the conventional load shedding method frequency settings, time delay settings and the amount of load to be shed in each step are constant values. The loads to be shed by this scheme are also constant load feeders and are not selected adaptively. Using this constant non-adaptive load shedding algorithm is not the most efficient scheme for all power system disturbances. In some combinational disturbances, events causing frequency to drop are followed by other events causing voltage drop. In these cases, since loads are voltage dependent, total system load is reduced and system frequency might not decrease so much to activate UFLS relays. However, the system could eventually collapse due to voltage instability. In many such cases the system would survive if the load shedding relays operate adaptively and appropriately. For example if for large disturbances, higher frequency settings and lower time delays are used adaptively, a faster load shedding response is obtained and as a result system collapses may be prevented. In this paper a new UFLS algorithm is proposed. The purpose of this algorithm is to adaptively adjust speed of load shedding based on the magnitude of disturbance. In this method rate of frequency decline is used as a criterion to determine intensity of disturbance. Thereby, for large disturbances higher frequency settings and lower time delays are used. Application of the proposed algorithm to the simulated model of Khorasan network in Iran confirms its satisfactory performance. As the results of simulations show, several voltage collapse instabilities may be prevented by using the proposed adaptive UFLS method.
Maryam Hourali; Mohammad Fathian; Abbas Montazeri; Mansoureh Hourali
Abstract
The current dynamic and turbulent business environment has forced companies that are competing in global markets to change their traditional methods of conducting business. Recent developments in applying Information Technology (IT) offer the most exciting business opportunities in the marketplace. Organizations ...
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The current dynamic and turbulent business environment has forced companies that are competing in global markets to change their traditional methods of conducting business. Recent developments in applying Information Technology (IT) offer the most exciting business opportunities in the marketplace. Organizations must re-evaluate every aspect of their strategies and quickly move to a working mode where the electronic commerce is essential for their success. One of tools that can be used for measuring the diffusion rate of IT is e-readiness assessment. Small and Medium Enterprises (SMEs) are critical to the economies of all countries, including developing ones. They cannot be left behind and many are already demonstrating their entrepreneurship strength by grasping opportunities offered by IT. The concept of e-readiness assessment for SMEs has received limited attention in the literature.
This paper first studies e-readiness assessment models proposed for countries and then tries to develop a model for measuring the e-readiness of SMEs (ESME) by an exploratory study. Finally, the proposed model is used for the assessment and comparison for e-readiness of three considered Iranian SMEs.
Afsaneh Sheykh Mohammadi; Yadollah Mortazavi; Abbas Ali Khodadadi; Yousef Zeynali
Abstract
We report the development of different types of oxygen sensors based on yittria-stabilized zirconia (YSZ) as a solid electrolyte. The conventional oxygen sensor is a concentration cell with two porous Pt electrodes, one of which is exposed to air as a constant (reference) oxygen concentration and the ...
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We report the development of different types of oxygen sensors based on yittria-stabilized zirconia (YSZ) as a solid electrolyte. The conventional oxygen sensor is a concentration cell with two porous Pt electrodes, one of which is exposed to air as a constant (reference) oxygen concentration and the other is exposed to automobile exhaust gas of variable oxygen concentration, depending on the air-to-fuel (ATF) ratio injected into engine. The conventional sensor is miniaturized by using an oxide semiconductor instead of the reference air. This the response time and the sensitivity of the sensor significantly improved. Also the light-off time, during which most of large city pollutant are dramatically reduced. The transition response of above sensors occur at the stoichiometric ATF ratio, while recently lean-burn engines working at ATF ratios higher than that of stoichiometric are proffered. In addition to the above sensors, we have developed a new type of YSZ- based oxygen sensor, in which two oxides (e.g. TiO2, SnO2 and CeO2) with different semi conductive characteristics are applied on the tow Pt electrodes. This way the transition response of the sensor is shifted toward ATF ratios higher than the stoichiometric ones, suitable for lean-burn engines.
Caren Abrinia; Rahim Tahriri Masoule
Abstract
Many metal forming problems have been solved using the slip line field method but all of them have either been two-dimensional (plane strain or plain stress) or axisymmetric problems. In this paper a procedure has been proposed by which the slip line field solution to three dimensional problems of metal ...
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Many metal forming problems have been solved using the slip line field method but all of them have either been two-dimensional (plane strain or plain stress) or axisymmetric problems. In this paper a procedure has been proposed by which the slip line field solution to three dimensional problems of metal forming becomes possible. For this purpose the extrusion of shaped sections has been taken as a case study. For this problem the geometry of the deforming zone has been defined by streamlines and stream surfaces. Clearly for the three dimensional extrusion of shaped sections the stream surfaces are not plane surfaces, and on the other hand the slip line field formulation could only be applied to plane surfaces, therefore an approximation has been made to accommodate this difficulty. In fact the three dimensional surface has been approximated to a plane surface so that for each three dimensional stream surface there exists an approximate plane surface. Unlike the case for the axisymmetric problem where there was only one plane surface on which the formulation was defined and the revolved 360 degrees to complete the deforming zone here there are many plane stream surfaces that by summing them up together the deforming zone is defined. The slip line field formulation was then applied to each and every one of these surfaces and the extrusion pressure on each surface was calculated separately and by adding up all the components of the pressure on each surface the total extrusion pressure was obtained.
To account for the error evolved from the approximations made in the formulations, error functions were developed which showed how much error was developed due to the approximations. To verify the results comparison were made to the results obtained by upper bound and experimental methods. These comparisons showed very good agreements.
Dara Moazzami
Abstract
Numerous networks as, for example, road networks, electrical networks and communication networks can be modeled by a graph. Many attempts have been made to determine how well such a network is "connected" or stated differently how much effort is required to break down communication in the system between ...
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Numerous networks as, for example, road networks, electrical networks and communication networks can be modeled by a graph. Many attempts have been made to determine how well such a network is "connected" or stated differently how much effort is required to break down communication in the system between at least some nodes. Two well-known measures that indicate how "reliable" a graph is are the "Tenacity" and "Edge-tenacity" of a graph. In this paper we present results on the tenacity and edge-tenacity, $T_e(G)$, a new invariant, for several classes of graphs. Basic properties and some bounds for edge-tenacity, $T_e(G)$, are developed. Edge-tenacity values for various classes of graphs are calculated and future work andconcluding remarks are summarized
Mahmoud Shariati; Masoud Mehdizadeh Rokhi
Abstract
Understanding how a cutout influences the load bearing capacity and buckling behavior of cylindrical shells is fundamental in the design of structural components used in automobiles, aircrafts, and marine structures. In this article, simulation and analysis of steel cylindrical shells with various lengths, ...
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Understanding how a cutout influences the load bearing capacity and buckling behavior of cylindrical shells is fundamental in the design of structural components used in automobiles, aircrafts, and marine structures. In this article, simulation and analysis of steel cylindrical shells with various lengths, include quasi elliptical cutout, subjected to axial compression were systematically carried out using finite element numerical method and the investigation examined the influence of the cutout size, cutout angle and the shell aspect ratio (L/D) on the buckling, and postbuckling responses of the moderately thick steel cylindrical shells. For several specimens an experimental investigation was also carried out via an INSTRON 8802 servo hydraulic machine. And the results obtained from the experiments were compared with numerical results. A very good accordance was observed between the results obtained from the finite element simulation and the experiments. Finally, corresponding to experimental and numerical results, an equation was presented for finding buckling load of such structures.
S. Jabari; Dara Moazzami; A. Ghodousian
Abstract
In this paper, we study the Generalized Bin Covering problem. For this problem an exact algorithm is introduced which can nd optimal solution for small scale instances. To nd a solution near optimal for large scale instances, a heuristic algorithm has been proposed. By computational experiments, the ...
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In this paper, we study the Generalized Bin Covering problem. For this problem an exact algorithm is introduced which can nd optimal solution for small scale instances. To nd a solution near optimal for large scale instances, a heuristic algorithm has been proposed. By computational experiments, the eciency of the heuristic algorithm is assessed.
Alessandro Rosa
Abstract
One widespread procedure to render the attractor of Kleinian groups, appearing in the renown book [8], wantshuge memory resources to compute and store the results. We present a new faster and lighter version that drops the original array and pulls out group elements from integers.
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One widespread procedure to render the attractor of Kleinian groups, appearing in the renown book [8], wantshuge memory resources to compute and store the results. We present a new faster and lighter version that drops the original array and pulls out group elements from integers.
Natasha Zamani; Asadollah Norzad; Anoushirvan Ansari
Abstract
In this paper the effects of uncertainties in the estimation of seismic hazard parameters is considered. These uncertainties are the result of the intricacy of the matter, restriction in identifying the interfering factors and lack of ability in determining the effective elements.
One of the methods ...
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In this paper the effects of uncertainties in the estimation of seismic hazard parameters is considered. These uncertainties are the result of the intricacy of the matter, restriction in identifying the interfering factors and lack of ability in determining the effective elements.
One of the methods in estimating the seismic hazard potential is probabilistic method. In this method with the hypothesis of an appropriate probable distribution for the site and distance; where the earthquake happens, from the considered site and by considering a probable time base distribution, we can determine the probability of various levels of a acceleration (or other seismic parameters).
in present time, the most appropriate method for determining the seismic parameters is a method named maximum likelihood .Although the basic methodologies used in seismic hazard analysis are well established, but the complex process of earthquake occurrence in a region and uncertainty in hazard modeling based on probabilistic method have some problems such as Simplification in modeling(without theoretical and experimental evidence) and Qualification in data(data with different level of noise).In this article is tried to pay the most attention to the problems and uncertainties of this method.
Maliheh Hashemipour; Mohammadreza Hooshmandasl; Ali Shakiba
Abstract
An outer connected dominating(OCD) set of a graph $G=(V,E)$ is a set $\tilde{D} \subseteq V$ such that every vertex not in $S$ is adjacent to a vertex in $S$, and the induced subgraph of $G$ by $V \setminus \tilde{D}$, i.e. $G [V \setminus \tilde{D}]$, is connected. The OCD number of $G$ is the smallest ...
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An outer connected dominating(OCD) set of a graph $G=(V,E)$ is a set $\tilde{D} \subseteq V$ such that every vertex not in $S$ is adjacent to a vertex in $S$, and the induced subgraph of $G$ by $V \setminus \tilde{D}$, i.e. $G [V \setminus \tilde{D}]$, is connected. The OCD number of $G$ is the smallest cardinality of an OCD set of $G$. The outer-connected bondage number of a nonempty graph G is the smallest number of edges whose removal from G results in a graph with a larger OCD number. Also, the outer-connected reinforcement number of G is the smallest number of edges whose addition to G results in a graph with a smaller OCD number. In 2018, Hashemi et al. demonstrated that the decision problems for the Outer-Connected Bondage and the Outer-Connected Reinforcement numbers are all NP-hard in general graphs. In this paper, we improve these results and show their hardness for bipartite graphs. Also, we obtain bounds for the outer-connected bondage number.
Iman Shojaei; Hossein Rahami
Abstract
In this paper a finite difference method for solving 2-dimensional diffusion equation is presented. The method employs Crank-Nicolson scheme to improve finite difference formulation and its convergence and stability. The obtained solution will be a recursive formula in each step of which a system of ...
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In this paper a finite difference method for solving 2-dimensional diffusion equation is presented. The method employs Crank-Nicolson scheme to improve finite difference formulation and its convergence and stability. The obtained solution will be a recursive formula in each step of which a system of linear equations should be solved. Given the specific form of obtained matrices, rather than solving the problem in each step using conventional iterative methods, a closed-form solution is formulated..
R. Vasuki; S. Suganthi; G. Pooranam
Abstract
Let G(V,E) be a graph with p vertices and q edges. A graph G is said to have an odd mean labeling if there exists a function f : V (G) → {0, 1, 2,...,2q - 1} satisfying f is 1 - 1 and the induced map f* : E(G) → {1, 3, 5,...,2q - 1} defi ned by
f*(uv) = (f(u) + f(v))/2 if f(u) ...
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Let G(V,E) be a graph with p vertices and q edges. A graph G is said to have an odd mean labeling if there exists a function f : V (G) → {0, 1, 2,...,2q - 1} satisfying f is 1 - 1 and the induced map f* : E(G) → {1, 3, 5,...,2q - 1} defi ned by
f*(uv) = (f(u) + f(v))/2 if f(u) + f(v) is evenf*(uv) = (f(u) + f(v) + 1)/2 if f(u) + f(v) is odd
is a bijection. A graph that admits an odd mean labeling is called an odd mean graph. In this paper, we have studied an odd meanness property of the subdivision of the slanting ladder SLn for all n ≥ 2; Cn Θ K1 for n ≥ 3; the grid Pm × Pn for m, n ≥ 2; Cm@Cn for m, n ≥ 3 and P2m Θ nK1 for all m, n ≥ 1..
Dara Moazzami; Niloofar Vahdat
Abstract
In general, computation of graph vulnerability parameters is NP-complete. In past, some algorithms were introduced to prove that computation of toughness, scattering number, integrity and weighted integrity parameters of interval graphs are polynomial.
In this paper, two different vulnerability parameters ...
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In general, computation of graph vulnerability parameters is NP-complete. In past, some algorithms were introduced to prove that computation of toughness, scattering number, integrity and weighted integrity parameters of interval graphs are polynomial.
In this paper, two different vulnerability parameters of graphs, tenacity and rupture degree are defined.
In general, computing the tenacity of a graph is NP-hard and the rupture degree of a graph is NP-complete, but in this paper, we will show that these parameters can be computed in polynomial time for interval graphs.
Dara Moazzami
Abstract
The analysis of vulnerability in networks generally involves some questionsabout how the underlying graph is connected. One is naturally interestedin studying the types of disruption in the network that maybe causedby failures of certain links or nodes. In terms of a graph, the concept ofconnectedness ...
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The analysis of vulnerability in networks generally involves some questionsabout how the underlying graph is connected. One is naturally interestedin studying the types of disruption in the network that maybe causedby failures of certain links or nodes. In terms of a graph, the concept ofconnectedness is used in different forms to study many of the measuresof vulnerability. When certain vertices or edges of a connected graphare deleted, one wants to know whether the remaining graph is stillconnected, and if so, what its vertex - or edge - connectivity is. If on theother hand, the graph is disconnected, the determination of the number ofits components or their orders is useful. Our purpose here is to describeand analyses the current status of the vulnerability measures, identify itsmore interesting variants, and suggest a most suitable measure ofvulnerability.
Maryam Biglari; Abossamad Zarrin Ghalam Moghaddam; Mohammad Reza Nasrin Omidkhah
Amir Pakdel; Masoud Emami; Hassan Farhangi; Mohammad Habibi Parsa
Abstract
Al-SiC composites are among the most demanding metal matrix composites due to their excellent strength, good ductility, good corrosion resistance, low coefficient of thermal expansion and reasonable price. Manufacturing of cast metal matrix composites usually involves some problems such as inhomogeneous ...
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Al-SiC composites are among the most demanding metal matrix composites due to their excellent strength, good ductility, good corrosion resistance, low coefficient of thermal expansion and reasonable price. Manufacturing of cast metal matrix composites usually involves some problems such as inhomogeneous distribution of the particles due to poor wetability of ceramics to molten alloys, porosity and formation of particle-void clusters. Thus it seems necessary to utilize secondary processes for these materials in order to obtain suitable properties. In this research Al6061 composites reinforced with 10 volume percent SiC particles of 48?m average size were produced by the stir casting method and effect of extrusion process on the microstructure and strength of these materials was investigated. Results showed that the average particle size and porosity of the composite samples decreased after extrusion. Moreover, tensile strength of the composite increased by increasing the extrusion temperature and/or the extrusion ratio since the pores in the microstructure diminished and the interface bonding was improved.
