Mehdi Takaffoli; Aghil Yusefikoma
Abstract
Numerical modeling of machining processes is of significance in the parametric analysis and optimization of their performance. In this paper, a finite element-based model of abrasive waterjet (AWJ) cutting of a ductile material is presented with the help of an explicit, nonlinear finite element method. ...
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Numerical modeling of machining processes is of significance in the parametric analysis and optimization of their performance. In this paper, a finite element-based model of abrasive waterjet (AWJ) cutting of a ductile material is presented with the help of an explicit, nonlinear finite element method. In this model, both solid-solid interaction and fluid-structure interaction are considered. The water is modeled as an Eulerian volume. The Euler-Lagrange coupling algorithm is employed to simulate the interaction of the waterjet with the abrasive particle and the target material. An elastic-plastic behavior is defined for the target material and the abrasive particle is assumed spherical, which behaves like an elastic material. The erosion of the target due to the AWJ impact is simulated using the element deletion approach. The variation of the depth of cut with respect to the waterjet pressure is estimated and compared with experimental results.
Ali Ammari Allahyari; Hassan Farhangi; Seyyed Mohammad Mehdi Hadavi
Abstract
The effects of isothermal aging at temperatures between 550-850 ?C for durations of 1-100 h on microstructure, tensile properties, and impact fracture behavior of 316L austenitic stainless steel weld metal have been investigated. For this purpose, various techniques including metallographic observations, ...
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The effects of isothermal aging at temperatures between 550-850 ?C for durations of 1-100 h on microstructure, tensile properties, and impact fracture behavior of 316L austenitic stainless steel weld metal have been investigated. For this purpose, various techniques including metallographic observations, measurement of ferrite content using ferritscope, and fractographic investigations have been utilized. It was found that increasing aging temperature and time lead to dissolution of delta ferrite and formation of a continuous network of sigma phase, followed by partial spherodization of sigma phase. These microstructural changes are found to induce a transition from ductile to brittle fracture mode which is accompanied by a sharp decrease in fracture strain and charpy impact energy, of up to 90%, and is characterized by specific types of fragmented and brittle microvoid fracture surface morphologies. The consequences of such behavior in regards to the selection of proper stress relief heat treatment temperature are discussed based on dividing the aging processing window into three distinct regions.
Davoud Ali Jamshidi; Bahram Navay'i Nia; Javad Vaseghi Amiri
Abstract
Because of different behavior of reservoir water and dam material, the determination of hydrodynamic pressure during earthquake is very complicated. Thus, different formulations have been presented for modeling of the dam reservoir system under dynamic loading such as earthquake. These formulations can ...
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Because of different behavior of reservoir water and dam material, the determination of hydrodynamic pressure during earthquake is very complicated. Thus, different formulations have been presented for modeling of the dam reservoir system under dynamic loading such as earthquake. These formulations can be categorized into two general groups, which are Lagrangian and Eulerian, each having advantages and disadvantages. In this paper, a proper formulation is presented for modeling of reservoir of concrete dams and determination of the hydrodynamic pressure based on finite element, and the Lagrangian and Eulerian methods. The Lagrangian and Eulerian methods are then compared with together for the determination of hydrodynamic pressure on the dam upstream and the displacement of the crest of dam for a variety of dimensions of dam under different types of earthquake. The results brought up from these two formulations are then compared with each other in different aspects such as accuracy, the required amount of calculations, the frequency effect, the boundary conditions, the dam upstream slope, the sediment in energy absorption, the reservoir height and its bed slope and eventually, the type of elements used in finite element method.
Furthermore, the formulation of reservoir using Lagrangian method for applying boundary conditions as especial element has been used and the results show that this method is an improvement of the existing finite element method in comparison with usual Lagrangian method in other to decrease the degree of freedom.
Ali Reza Soltankouhi; Khosro Bargi
Abstract
Breakwaters are the important and the costly ones of the marine structures. Composite breakwater is one of the common types in the world. Because of the sensitivity of composite breakwaters to environmental conditions, also construction costs, difficulty of repair and maintenance and importance of equipments ...
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Breakwaters are the important and the costly ones of the marine structures. Composite breakwater is one of the common types in the world. Because of the sensitivity of composite breakwaters to environmental conditions, also construction costs, difficulty of repair and maintenance and importance of equipments on and behind the breakwater, design of composite breakwater must be very accurate. Goal of present research is assessment of effect of environmental parameters in design of composite breakwater. In this way sensitivity of geometric parameters of this structure to hydraulic specifications such as period, height and direction of waves and depth of water, has been analyzed. Also effect of sea bed soil type in dimensions of this structure has been evaluated. Comparison between analytical and experimental formulas in evaluation of wave forces on composite breakwaters has been done. The results of this research have been expressed in some applied graphs for evaluation of effects of hydraulic and geotechnic parameters in dimensions of composite breakwaters. Thus results of present work can be used for attentively design of these structures in different environmental conditions of sea.
Mahmoud Mehrdad Shokrieh; Fathollah Taheri Behrouz
Keyvan Hosseini Safari; Mahmoud Mousavi Mashhadi
Abstract
Determination of the optimum loading path (internal pressure- axial feeding) to restrict the Bursting, buckling and wrinkling through tube hydroforming process is necessary to produce an acceptable tube. In this paper, the wrinkling and fracture criteria are implemented to an finite element code devoted ...
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Determination of the optimum loading path (internal pressure- axial feeding) to restrict the Bursting, buckling and wrinkling through tube hydroforming process is necessary to produce an acceptable tube. In this paper, the wrinkling and fracture criteria are implemented to an finite element code devoted to the simulation of tube hydroforming processes. Using the ANSYS parametric design language (APDL), two macros are built to compute the value of bursting and wrinkling indicators through the elements. By determining the indicators values through the step to step solution of the software, it is possible that compares them with critical values and predicts the fracture and wrinkling in tube hydroforming process.
Mahmoud Golabchi; Mohammad Hassan Sebt; Hossein Naghash Tousi
Abstract
One of the common questions in all projects, is "How much would be the final cost of the project?" or "How much would be the completion duration of the project?". Earned Value Management presents a method for estimation of these results. In general methods and formula of Earned Value Management, future ...
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One of the common questions in all projects, is "How much would be the final cost of the project?" or "How much would be the completion duration of the project?". Earned Value Management presents a method for estimation of these results. In general methods and formula of Earned Value Management, future trend of project, are anticipated completely based on its previous trend, and changes in environmental conditions or other effective elements in future performance of the project are neglected. But risk management looks a future horizon in project's future and explores unknown future to identify potential threats and opportunities and control their occurrence results on project performance. In this paper, using risk management process and challenging effective aspects & elements on project future performance in different visions, a risk coefficient in accordance with current coefficient of "EVMS", is presented for better estimate of final results of projects. The goal of this method is concentration of management's attention on reaching project goals, by using interaction of these two methods in determining exact performance coefficient of project future. Anticipating exact results of project is attainable by this coefficient.
Nikzad Nourpanah; Moharram Dolatshahi Pirooz
Abstract
Development of a numerical model which describes launching of offshore jackets from barge is presented in this paper. In this model, in addition to capabilities of commercial softwares, water entry forces on jacket members and an implicit Newmark solution technique are included. The results are in general ...
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Development of a numerical model which describes launching of offshore jackets from barge is presented in this paper. In this model, in addition to capabilities of commercial softwares, water entry forces on jacket members and an implicit Newmark solution technique are included. The results are in general agreement with other numerical software’s available (SACS). Fluid forces acting on jacket and the importance of each one is discussed. It is observed that water entry forces on horizontal jacket members are very significant and may locally govern the design of these members. This force is more important for horizontal slender members near the mud-line, which do not experience significant environmental loading in operating conditions. Therefore the water entry impact force with large magnitude can cause over-stress and/or ovalling of near mud-line members. It is also observed that taking water entry forces in account modifies the jacket trajectory only in a little extent.
Mohammad Shariyat; Abbas Ganjipour
Abstract
In the present paper, employing a complete model of a passenger car, contribution of various components and assemblies in the frontal crash energy absorption is determined. Thickness of components with more remarkable contribution is increased to improve the occupant safety. Furthermore, effects of substituting ...
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In the present paper, employing a complete model of a passenger car, contribution of various components and assemblies in the frontal crash energy absorption is determined. Thickness of components with more remarkable contribution is increased to improve the occupant safety. Furthermore, effects of substituting the metallic bumper with one fabricated from GMT materials on the frontal crash behavior of the vehicle are investigated. Boundary condition and dynamic parameters are defined in PAM-CRASH software. To increase the accuracy of the results, all sub-assemblies and their joints are precisely modeled. Finally, components with more remarkable contribution in energy absorption are detected and a comparison is made between the crash results of the original design and the crash results obtained after the mentioned modifications.
Ghader Faraji; Mohammad Kazem Besharati Givi; Saeed Yarmohammadi; Mahmoud Mousavi Mashhadi
Abstract
Deep drawing of cylindrical shapes with high limiting drawing ratio (LDR) values is relatively difficult. Annealing is a further operation, which in turn adds costs and consumes significantly time to the forming process. In the present work, cylindrical cups from brass sheet were made with only limited ...
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Deep drawing of cylindrical shapes with high limiting drawing ratio (LDR) values is relatively difficult. Annealing is a further operation, which in turn adds costs and consumes significantly time to the forming process. In the present work, cylindrical cups from brass sheet were made with only limited anneal during few steps, but having LDR of 9 that is about 2 times higher than previous works. Cups having 4 mm IDs and 70 mm heights were made successfully. The process was simulated by ABAQUS/Explicit finite element (FE) code and experimental tests were carried out based on FEM results. Parameters affecting the process were studied with experimental results, as well as FEM. The wall thickness obtained from the approach were compared for several tests, and verified significantly.
Amin Samadi Ghoushchi; Caren Abrinia; Mohammad Kazem Besharati Givi
Abstract
Slab method of analysis has been used for solving metal forming problems for a long time. However it has been restricted to plane strain and axisymmetric problems due to limitations in its formulations. In this paper a new formulation has been proposed so that it could be applied to three dimensional ...
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Slab method of analysis has been used for solving metal forming problems for a long time. However it has been restricted to plane strain and axisymmetric problems due to limitations in its formulations. In this paper a new formulation has been proposed so that it could be applied to three dimensional problems in metal forming. A parametric slab has been considered in this analysis and the force balance on the slab was carried to obtain equilibrium equations in terms of these parameters. The parameters in fact are related to the geometry of the final extruded shape, the die and the material flow regime assumed in the formulation. In this way most of the limitations encountered in previous formulations were surpassed. The effect of reduction of area, frictional conditions and other process parameters on the extrusion pressure was investigated. The theoretical results obtained in this paper were compared with the results of finite element method and a good agreement was observed between them.
Farshad Kowsari; Seyyed Morteza Azimi
Abstract
In this paper the optimal control of boundary heat flux in a 2-D solid body with an arbitrary shape is performed in order to achieve the desired temperature distribution at a given time interval. The boundary of the body is subdivided into a number of components. On each component a time-dependent heat ...
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In this paper the optimal control of boundary heat flux in a 2-D solid body with an arbitrary shape is performed in order to achieve the desired temperature distribution at a given time interval. The boundary of the body is subdivided into a number of components. On each component a time-dependent heat flux is applied which is independent of the others. Since the thermophysical properties are temperature-dependent, the problem is treated as a nonlinear inverse heat conduction problem. Conjugate gradient method (CGM) along with adjoint problem is utilized in order to solve the inverse problem. Optimization process is employed for the heat flux imposed on each of the boundary component individually which was previously shown to be more efficient than optimizing the entire heat flux array simultaneously. Three versions of CGM; that is, the Fletcher-Reeves (FR), Polak-Ribiere (PR) and Powell-Beale are utilized for comparison. As a test case, heating of an Aluminum bar with a square cross section and temperature-dependent thermo-physical properties is considered. Results show that for large time-steps the Powell-Beale version with normalized search direction, and for small time-steps the Polak-Ribiere version are the most efficient method with the least error in the estimated temperature field. Moreover, for large time step size results show that addition of regularization term to the Error Function reduces the amplitude of oscillations in the estimated heat flux.
Seyyed Masoud Marandi; Mehdi Tajdari; Khosro Rahmani
Abstract
Foreign object damage (FOD) occurs when hard, millimeter-sized objects such as gravel or sand and even the pieces of the engine components are ingested into aircraft jet engines. Particles impacting blades produce small indentation craters which can become sites for fatigue crack initiation, severely ...
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Foreign object damage (FOD) occurs when hard, millimeter-sized objects such as gravel or sand and even the pieces of the engine components are ingested into aircraft jet engines. Particles impacting blades produce small indentation craters which can become sites for fatigue crack initiation, severely limiting the lifetime of the blade. In this study, the impact on the edge of a thin plate is investigated by using the finite element method. Then residual stresses are compared between the quasi-static indentation and fully dynamic impact for three critical locations where the residual hoop stresses are tensile. At the end, experimental stress analysis is performed for investigating the stress concentration factor at the crater base and comparing with data from the finite element method. The comparison shows that the finite element method result agrees well with experimental data at the crater base.
Abdorrasoul Mayyahi; Aghil Yousefikoma; Ali Rangin Kaman; Hesam Maleki
Abstract
An autonomous underwater vehicle (AUV) with less noise and vortices as well as efficient power consumption, is pursued in this research by inspiration of shark swimming. Design, hydrodynamic analysis, modeling, fabrication, navigation, and control of this novel AUV is the main goal of this research. ...
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An autonomous underwater vehicle (AUV) with less noise and vortices as well as efficient power consumption, is pursued in this research by inspiration of shark swimming. Design, hydrodynamic analysis, modeling, fabrication, navigation, and control of this novel AUV is the main goal of this research. Detailed explanation of the test and experiment with a brief overview on fabrication are provided. The transfer function of the system has been extracted from the experimental data. The transfer function is then employed for dynamic analysis and control system development. Zigler-Nickols method is used to predetermine the PID control coefficients. Consequently, small modifications have been done by trial and error. Trajectory control in a 10 cm off the wall and in a 20 cm band in a large swimming pool has been examined by a 3 DOF AUV.
Ali Naserian; Masoud Tahani
Abstract
The Levy-type analytical solution is employed for the problem of bending of cross-ply and antisymmetric angle-ply piezoelectric hybrid laminated plates with at least two simply supported opposite edges. The governing equations of equilibrium are derived in the framework of the first-order shear deformation ...
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The Levy-type analytical solution is employed for the problem of bending of cross-ply and antisymmetric angle-ply piezoelectric hybrid laminated plates with at least two simply supported opposite edges. The governing equations of equilibrium are derived in the framework of the first-order shear deformation plate theory. The equations are classified according to the crystallography type of piezoelectric layers and a comprehensive discussion on limitations of the method for the analysis of this kind of structures is performs. Finally, the governing equations of equilibrium are solved analytically with the aid of the state-space approach. We concluded that during the analysis of piezoelectric hybrid laminated plates with Levy-type method, simultaneous applying of all electrical forces and moments is not possible (depending on type of lay-up, crystallography of piezoelectric layers, and expansion of electrical potential, some of electrical forces and moments may not be considered). In order to study the accuracy and convergence rate of the proposed method, several numerical examples are examined. The numerical results are compared with those obtained by the Navier method and those presented in the other published articles. It is found that the present results have very good agreements with those obtained by other methods.
Vahid Norouzifard; Aghil Yousefikoma
Abstract
The built up layer thickness in secondary deformation zone is one of the important parameters in metal cutting process. The built up layer (BUL) is formed in second deformation zone near the tool-chip interface in the back of the chip. This parameter influences the tool life and machined surface quality. ...
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The built up layer thickness in secondary deformation zone is one of the important parameters in metal cutting process. The built up layer (BUL) is formed in second deformation zone near the tool-chip interface in the back of the chip. This parameter influences the tool life and machined surface quality. This BUL should not be confused with the built up edge (BUE). The deformation of the BUL in the secondary shear zone is a stable and continues process; leading to an uniform thickness of the BUL along the chip's back but the deformation of the BUE is an unstable process in front of the tool edge. Numerical simulation is a suitable method for determination of temperature, stress and strain distribution in metal cutting since it dose not suffer the analytical methods limitations and experimental methods cost. In this paper a new method is presented to calculate the built up layer thickness in secondary deformation zone using finite element simulation of orthogonal metal cutting process. There are two main concepts about chip separation mechanisms from work piece, i. e. crack propagation and pour deformation without crack. In the present work chip formation process is assumed as a pour plastic deformation, considering second chip separation mechanism. There is no separation criterion in the simulations based on pour deformation, but Adaptive remeshing is performed during simulation to avoid the difficulties associated with deformation-induced element distortion. An updated Lagrangian finite element model of two-dimensional orthogonal cutting process is developed. This model is meshed using 4-node plain strain elements. Thermo-mechanical coupled analysis, with adaptive remeshing is performed by LS-DYNA finite element code. Johnson-Cook material model is used for determination of the work piece material flow stress and the cutting tool is assumed as a rigid body. An updated coulomb friction law is used to describe friction condition in tool-chip interface. The temperature and equivalent strain distribution diagrams in cutting zone are shown at various cutting speeds. The built up layer thickness in various cutting speed are also calculated by equivalent strain gradient in second deformation zone. The numerical calculated tool average temperatures and the built up layer thicknesses in various cutting speeds are compared with the experimental data given in literature and good agreement is observed between them.
Bertrand Teguia Tabuguia
Abstract
Linear and homogeneous recurrence equations having polynomial coefficients are said to be holonomic. These equations are useful for proving and discovering combinatorial and hypergeometric identities. Given a field $\mathbb{K}$ of characteristic zero, $a_n$ is a hypergeometric term with respect to $\mathbb{K}$, ...
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Linear and homogeneous recurrence equations having polynomial coefficients are said to be holonomic. These equations are useful for proving and discovering combinatorial and hypergeometric identities. Given a field $\mathbb{K}$ of characteristic zero, $a_n$ is a hypergeometric term with respect to $\mathbb{K}$, if the ratio $a_{n+1}/a_n$ is a rational function over $\mathbb{K}$. Two algorithms by Marko Petkov\v{s}ek (1993) and Mark van Hoeij (1999) were proposed to compute hypergeometric term solutions of holonomic recurrence equations. The latter algorithm is more efficient and was implemented by its author in the Computer Algebra System (CAS) Maple through the command \texttt{LREtools[hypergeomsols]}. We describe
a variant of van Hoeij's algorithm that performs with the same efficiency without considering certain recommendations of the original version. We implemented our algorithm in the CASes Maxima and Maple. It also appears for some particular cases that our code finds results where \texttt{LREtools[hypergeomsols]} fails.
Our implementation is part of the \texttt{FPS} software which can be downloaded at \url{http://www.mathematik.uni-kassel.de/~bteguia/FPS_webpage/FPS.htm}. The command is \texttt{HypervanHoeij} for Maxima 5.44 and \texttt{rectohyperterm} for Maple 2021.
Abstract
Linear and homogeneous recurrence equations having polynomial coefficients are said to be holonomic. These equations are useful for proving and discovering combinatorial and hypergeometric identities. Given a field $\mathbb{K}$ of characteristic zero, $a_n$ is a hypergeometric term with respect to $\mathbb{K}$, ...
Read More
Linear and homogeneous recurrence equations having polynomial coefficients are said to be holonomic. These equations are useful for proving and discovering combinatorial and hypergeometric identities. Given a field $\mathbb{K}$ of characteristic zero, $a_n$ is a hypergeometric term with respect to $\mathbb{K}$, if the ratio $a_{n+1}/a_n$ is a rational function over $\mathbb{K}$. Two algorithms by Marko Petkov\v{s}ek (1993) and Mark van Hoeij (1999) were proposed to compute hypergeometric term solutions of holonomic recurrence equations. The latter algorithm is more efficient and was implemented by its author in the Computer Algebra System (CAS) Maple through the command \texttt{LREtools[hypergeomsols]}.
We describe a variant of van Hoeij's algorithm that performs with the same efficiency without considering certain recommendations of the original version. We implemented our algorithm in the CASes Maxima and Maple. It also appears for some particular cases that our code finds results where \texttt{LREtools[hypergeomsols]} fails.
Abstract
A popular research topic in Graph Convolutional Networks (GCNs) is to speedup the training time of the network. The main bottleneck in training GCN is the exponentially growing of computations. In Cluster-GCN based on this fact that each node and its neighbors are usually grouped ...
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A popular research topic in Graph Convolutional Networks (GCNs) is to speedup the training time of the network. The main bottleneck in training GCN is the exponentially growing of computations. In Cluster-GCN based on this fact that each node and its neighbors are usually grouped in the same cluster, considers the clustering structure of the graph, and expand each node's neighborhood within each cluster when training GCN.The main assumption of Cluster-GCN is the weak relation between clusters; which is not correct at all graphs. Here we extend their approach by overlapped clustering, instead of crisp clustering which is used in Cluster-GCN. This is achieved by allowing the marginal nodes to contribute to training in more than one cluster. The evaluation of the proposed method is investigated through the experiments on several benchmark datasets.The experimental results show that the proposed method is more efficient than Cluster-GCN, in average.
Abstract
\noindent Let $G = (V, E)$ be a $(p,q)$ graph.\\Define \begin{equation*}\rho =\begin{cases}\frac{p}{2} ,& \text{if $p$ is even}\\\frac{p-1}{2} ,& \text{if $p$ is odd}\\\end{cases}\end{equation*}\\ and $L = \{\pm1 ,\pm2, \pm3 , \cdots ,\pm\rho\}$ called the set of labels.\\\noindent ...
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\noindent Let $G = (V, E)$ be a $(p,q)$ graph.\\Define \begin{equation*}\rho =\begin{cases}\frac{p}{2} ,& \text{if $p$ is even}\\\frac{p-1}{2} ,& \text{if $p$ is odd}\\\end{cases}\end{equation*}\\ and $L = \{\pm1 ,\pm2, \pm3 , \cdots ,\pm\rho\}$ called the set of labels.\\\noindent Consider a mapping $f : V \longrightarrow L$ by assigning different labels in L to the different elements of V when p is even and different labels in L to p-1 elements of V and repeating a label for the remaining one vertex when $p$ is odd.The labeling as defined above is said to be a pair difference cordial labeling if for each edge $uv$ of $G$ there exists a labeling $\left|f(u) - f(v)\right|$ such that $\left|\Delta_{f_1} - \Delta_{f_1^c}\right| \leq 1$, where $\Delta_{f_1}$ and $\Delta_{f_1^c}$ respectively denote the number of edges labeled with $1$ and number of edges not labeled with $1$. A graph $G$ for which there exists a pair difference cordial labeling is called a pair difference cordial graph. In this paper we investigate pair difference cordial labeling behavior of planar grid and mangolian tent graphs.
Abstract
In this paper, a type of fuzzy system is firstly investigated whereby the feasible region is defined by the fuzzy relational equalities and the geometric mean as fuzzy composition. Some related basic and theoretical properties are derived and the feasible region is completely determined. Moreover, a ...
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In this paper, a type of fuzzy system is firstly investigated whereby the feasible region is defined by the fuzzy relational equalities and the geometric mean as fuzzy composition. Some related basic and theoretical properties are derived and the feasible region is completely determined. Moreover, a comparison is made between this region and FRE defined by product t-norm. Finally, an example is described to illustrate the differences of these two FRE systems.
Abstract
We introduce a new invariant vulnerability parameter named “J-Tightness” or “J(G)” for graphs. As a stability measure, its properties along with comparisons to other parameters of a graph are proposed. We show how it is calculated for complete graphs and cycles. We show that J-Tightness ...
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We introduce a new invariant vulnerability parameter named “J-Tightness” or “J(G)” for graphs. As a stability measure, its properties along with comparisons to other parameters of a graph are proposed. We show how it is calculated for complete graphs and cycles. We show that J-Tightness better fits the properties of vulnerability measures and can be used with more confidence to assess the vulnerability of any classes of graphs.
Abstract
In this paper, a linear programming problem is investigated in which the feasible region is formed as a special type of fuzzy relational equalities (FRE). In this type of FRE, fuzzy composition is considered as the weighted power mean operator (WPM). Some theoretical properties of the feasible region ...
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In this paper, a linear programming problem is investigated in which the feasible region is formed as a special type of fuzzy relational equalities (FRE). In this type of FRE, fuzzy composition is considered as the weighted power mean operator (WPM). Some theoretical properties of the feasible region are derived and some necessary and sufficient conditions are also presented to determine the feasibility of the problem. Moreover, two procedures are proposed for simplifying the problem. Based on some structural properties of the problem, an algorithm is presented to find the optimal solutions and finally, an example is described to illustrate the algorithm.
Abstract
The statistical methods based on cumulative distribution function is a start point for many parametric or nonparametric statistical inferences. However, there are many practical problems that require dealing with observations/parameters that represent inherently imprecise. However, Hesamian ...
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The statistical methods based on cumulative distribution function is a start point for many parametric or nonparametric statistical inferences. However, there are many practical problems that require dealing with observations/parameters that represent inherently imprecise. However, Hesamian and Taheri (2013) was extended a concept of fuzzy cumulative distribution function. Applying a common notion of fuzzy random variables, they extended a vague concept of fuzzy cumulative distribution function. However, the main properties of the proposed method has not yet been considered in fuzzy environment. This paper aims to extend the classical properties of the fuzzy cumulative distribution function in fuzzy environment.
Abstract
In this paper, a linear programming problem is investigated in which the feasible region is formed as the intersection of fuzzy relational equalities and the harmonic mean operator is considered as fuzzy composition. Theoretical properties of the feasible region are derived. It is proved that the feasible ...
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In this paper, a linear programming problem is investigated in which the feasible region is formed as the intersection of fuzzy relational equalities and the harmonic mean operator is considered as fuzzy composition. Theoretical properties of the feasible region are derived. It is proved that the feasible solution set is comprised of one maximum solution and a finite number of minimal solutions. Furthermore, some necessary and sufficient conditions are additionally presented to determine the feasibility of the problem. Moreover, an algorithm is presented to find the optimal solutions of the problem and finally, an example is described to illustrate the algorithm.
