Niloofar Aghaieabiane; Henk Koppelaar; Peyman Nasehpour
Abstract
It is well-known that, given inorder traversal along with one of the preorder or postorder traversals of a binary tree, the tree can be determined uniquely. Several algorithms have been proposed to reconstruct a binary tree from its inorder and preorder traversals. There is one study to reconstruct a ...
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It is well-known that, given inorder traversal along with one of the preorder or postorder traversals of a binary tree, the tree can be determined uniquely. Several algorithms have been proposed to reconstruct a binary tree from its inorder and preorder traversals. There is one study to reconstruct a binary tree from its inorder and postorder traversals, and this algorithm takes running time of $ \BigO{\emph{n}^2} $. In this paper, we present $ \proc{InPos} $ an improved algorithm to reconstruct a binary tree from its inorder and postorder traversals. The running time and space complexity of the algorithm are an order of $ \BigTheta{\emph{n}} $ and $ \BigTheta{\emph{n}} $ respectively, which we prove to be optimal. The $ \proc{InPos} $ algorithm not only reconstructs the binary tree, but also it determines different types of the nodes in a binary tree; nodes with two children, nodes with one child, and nodes with no child. At the end, the $ \proc{InPos} $ returns a matrix-based structure to represent the binary tree, and enabling access to any structural information of the reconstructed tree in linear time with any given tree traversals.
Amir Mesrikhani; Mohammad Farshi; Behnam Iranfar
Abstract
Let $S$ be a set of imprecise points that is represented by axis-aligned pairwise disjoint squares in the plane. A precise instance of $S$ is a set of points, one from each region of $S$. In this paper, we study the optimal minimum spanning tree (\textit{OptMST}) problem on $S$. The \textit{OptMST} problem ...
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Let $S$ be a set of imprecise points that is represented by axis-aligned pairwise disjoint squares in the plane. A precise instance of $S$ is a set of points, one from each region of $S$. In this paper, we study the optimal minimum spanning tree (\textit{OptMST}) problem on $S$. The \textit{OptMST} problem looks for the precise instance of $S$ such that the weight of the MST in this instance, maximize (Max-MST) or minimize (Min-MST) between all precise instances of~$S$ under $L_1$-metric. We present a $(\frac{3}{7})$-approximation algorithm for Max-MST. This is an improvement on the best-known approximation factor of $1/3$. If $S$ satisfies $k$-separability property (the distance between any pair of squares are at least $k.a_{max}$ where $a_{max}$ is the maximum length of the squares), the factor parameterizes to $\frac{2k+3}{2k+7}$. We propose a new lower bound for Min-MST problem on $S$ under $L_1$-metric where $S$ contains unit squares and provide an approximation algorithm with $(1+2\sqrt{2})$ asymptotic factor.
Azadeh Sharafibadr; Zahra Nilforoushan
Abstract
We consider the problem of finding the localization of radioactive source by using data from a digital camera. In other words, the camera could help us to detect the direction of radioactive rays radiation. Therefore, the outcome could be used to command a robot to move toward the true direction to achieve ...
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We consider the problem of finding the localization of radioactive source by using data from a digital camera. In other words, the camera could help us to detect the direction of radioactive rays radiation. Therefore, the outcome could be used to command a robot to move toward the true direction to achieve the source. The process of camera data is performed by using image processing and computational geometry algorithms. And the robot is looking for the source in a space with geometrical obstacles. Lots of radioactive accidents daily occur all over the world. During the radiography, the radioactive source is sometimes thrown out from its protection layer and the radiographer has to look for it in the space around. This would have lots of irreparable costs. Thus, it seems necessary to make a robot which could search the radioactive source intelligently.
Iman Shojaei; Hossein Rahami
Abstract
Some near-regular mechanical systems involve global deviations from their corresponding regular system. Despite extensive research on vibration analysis (eigensolution) of regular and local near-regular mechanical systems, the literature on vibration analysis of global near-regular mechanical systems ...
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Some near-regular mechanical systems involve global deviations from their corresponding regular system. Despite extensive research on vibration analysis (eigensolution) of regular and local near-regular mechanical systems, the literature on vibration analysis of global near-regular mechanical systems is scant. In this paper, a method for vibration analysis of such systems was developed using Kronecker products and matrix manipulations. Specifically, the eigensolution of the corresponding regular mechanical system was inserted in the algorithm to further accelerate the solution. The developed method allowed reduction in computational complexity (i.e., $\mathrm{O}(n^2)$) when compared to earlier methods. The application of the method was indicated using a simple example.
Mehdi Shams; Gholamreza Hesamian
Abstract
This paper extends the sign test to the case where data are observations of fuzzy random variables, and the hypotheses are imprecise rather than crisp. In this approach, first a new notion of fuzzy random variables is introduced. Then, the $\alpha$-level sets of the imprecise observations are transacted ...
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This paper extends the sign test to the case where data are observations of fuzzy random variables, and the hypotheses are imprecise rather than crisp. In this approach, first a new notion of fuzzy random variables is introduced. Then, the $\alpha$-level sets of the imprecise observations are transacted to extend the usual method of sign test. To do this, the concepts of fuzzy median and fuzzy sample median are defined.We also develop a well-known large sample property of the classical sample median. In addition, the test statistic is extended for investigating fuzzy hypothesis. After that, applying an index called credibility degree, the degree that the observed fuzzy test statistics belongs to the critical region is evaluated. The result provides a fuzzy test function which leads to some degrees to accept or to reject the fuzzy null hypothesis.A numerical example is provided to clarify the discussions made in this paper.
P. Jeyanthi; A. Sudha
Abstract
A vertex irregular total k-labeling of a graph G with vertex set V and edge set E is an assignment of positive integer labels {1, 2, ..., k} to both vertices and edges so that the weights calculated at vertices are distinct. The total vertex irregularity strength of G, denoted by tvs(G)is the minimum ...
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A vertex irregular total k-labeling of a graph G with vertex set V and edge set E is an assignment of positive integer labels {1, 2, ..., k} to both vertices and edges so that the weights calculated at vertices are distinct. The total vertex irregularity strength of G, denoted by tvs(G)is the minimum value of the largest label k over all such irregular assignment. In this paper, we study the total vertex irregularity strength for n ≥ 3, m ≥ 2, Pn ⊙ K1, Pn ⊙ K2, Cn ⊙ K2, Ln ⊙ K1, CLn ⊙ K1, P2 ⊙ Cn, Pn ⊙ Km, Cn ⊙ Km
Akbar Eshaghi; Jafar Raiszadeh; Hamid Reza Ghasemi; Reza Taghiabadi
Abstract
The effect of T6 heat treatment on the microstructure and wear behavior of Al-332 piston alloy containing 1.2wt% iron was investigated. The results showed that the T6 heat treatment changed the morphology of acicular eutectic Si particles to a more spherical form. The heat treatment also reduced the ...
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The effect of T6 heat treatment on the microstructure and wear behavior of Al-332 piston alloy containing 1.2wt% iron was investigated. The results showed that the T6 heat treatment changed the morphology of acicular eutectic Si particles to a more spherical form. The heat treatment also reduced the average length and blunted the needle-like ?- phase intermetallics through dissolution and fragmentation. The results also showed that an increase in the time and temperature of the heat treatment decreased the length of the ?-phase by about 70 percent and further blunted it at solutionizing temperature of 520?C for 14h. The results also showed that heat treatment increased the wear resistance of the alloy by about 40 percent.
R Ponraj; J Maruthamani; R Kala
Abstract
In this paper we introduce a new graph labeling method called $k$-Total prime cordial. Let $G$ be a $(p,q)$ graph. Let $f:V(G)\to\{1,2, \ldots, k\}$ be a map where $k \in \mathbb{N}$ and $k>1$. For each edge $uv$, assign the label $gcd(f(u),f(v))$. $f$ is called $k$-Total prime cordial labeling of ...
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In this paper we introduce a new graph labeling method called $k$-Total prime cordial. Let $G$ be a $(p,q)$ graph. Let $f:V(G)\to\{1,2, \ldots, k\}$ be a map where $k \in \mathbb{N}$ and $k>1$. For each edge $uv$, assign the label $gcd(f(u),f(v))$. $f$ is called $k$-Total prime cordial labeling of $G$ if $\left|t_{f}(i)-t_{f}(j)\right|\leq 1$, $i,j \in \{1,2, \ldots, k\}$ where $t_{f}(x)$ denotes the total number of vertices and the edges labeled with $x$. We investigate k-total prime cordial labeling of some graphs and study the 4-total prime cordial labeling of path, cycle, complete graph etc.
Hamid Reza Shahverdi; Manouchehr Haghighi; Kazem Fouladi
Siamak Motahhari
Abstract
In the present research work, the flexural modulus and strength of glass fiber-epoxy resin and carbon fiber-epoxy resin composites have been enhanced through fiber tension during curing of the polymeric resin. This study showed that the tension applied on the fibers increased the flexural modulus of ...
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In the present research work, the flexural modulus and strength of glass fiber-epoxy resin and carbon fiber-epoxy resin composites have been enhanced through fiber tension during curing of the polymeric resin. This study showed that the tension applied on the fibers increased the flexural modulus of the glass-epoxy composites up to 12% and the flexural strength up to 19%. The flexural modulus and strength of carbon-epoxy were also increased up to 25% and 13%, respectively. It was shown that the optimum fiber tension to obtain the maximum flexural properties depends on the fiber the composite is made of. The mechanism through which the improvement has been achieved was also presented.
Majid Meybodian; Hossein Memarian; Mehdi Zare
Abstract
Sarcheshmeh copper mine, with the final reserves of 828 million tons of sulfur ore and average grade of 0.74%, is known to be the largest open pit of Iran and most probably the second largest copper mine in the world. This mine is located in the seismotectonic zone of Central-Iran, and 23 Km away from ...
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Sarcheshmeh copper mine, with the final reserves of 828 million tons of sulfur ore and average grade of 0.74%, is known to be the largest open pit of Iran and most probably the second largest copper mine in the world. This mine is located in the seismotectonic zone of Central-Iran, and 23 Km away from the 150 Km long Rafsanjan active fault.In this study the vulnerability of the west wall of the mine, which is more susceptible to sliding, is determined. First, the seismic hazard probability was calculated by defining seismic sources and determination of seismicity parameters. Then the most effective source in seismic hazard is determined by seismic hazard deaggregation. The Newmark displacement of the west wall is calculated by the critical acceleration and Arias intensity. Finally, the mine vulnerability and seismic risk for this site, along with the probable earthquakes, is calculated. The seismic risk of this site is estimated to be 0.07 of the overall value of the mine.
Mohammad Farough Hosseini; Soroush Fouladchi; Mojtaba Ganji
Abstract
Wave propagation is used as an advanced tool of determining elastic properties of rocks. In spite of being cheap and non destructive tests of rock mechanics, due to its modernity method is not yet replacing the traditional dear and destructive tests. In order to pave ways of replacing this test and making ...
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Wave propagation is used as an advanced tool of determining elastic properties of rocks. In spite of being cheap and non destructive tests of rock mechanics, due to its modernity method is not yet replacing the traditional dear and destructive tests. In order to pave ways of replacing this test and making best use of it all effective factors of such method are to be assessed. One fundamental factor affecting the test result is the shape of the specimen tested. The existing standards do not seriously take the sample shape into consideration. It was pointed out elsewhere that in spite of popular taught elastic dynamic properties do vary seriously due to variation of sample shape (height to diameter ratio). As this fact was revealed for limestone in our previous investigation this assessment was extended to other types of rocks for the possibility of true judgment. Therefore, ultrasonic wave propagation tests were conducted on four various rock types with height to diameter ratio of 0.5 to 3. Analyzing of the test results showed that shear wave velocity and elastic dynamic constants are noticeably dependent on sample height/diameter ratio. The variation of height/diameter ratio from 0.5 to 3 caused the variation of shear wave velocity and Poisson’s ratio up to 70%, Elasticity modulus up to 160% and shear modulus up to 200% as follows in details:
Variation in shear wave velocity: Limestone, 24%; Siltstone, 70%; Green Tuff, 17% and Granodiorite, 20%.
Variation in dynamic elastic modulus: Limestone, 26%; Siltstone, 65%; Green Tuff, 73% and Granodiorite, 33%.
Variation in Poisson’s ratio: Limestone, 45%; Siltstone, 160%; Green Tuff, 20% and Granodiorite, 35%.
Variation in shear modulus: Limestone, 53%; Siltstone, 200; Green Tuff, 38% and Granodiorite, 45%.
It was also observed that the longitudinal wave velocity was not following the height/diameter ratio and showed no specific trend of variation.
As seen from the above details, the variation of modulai is much grater for siltstone in compares to the 3 other rocks. It is most likely that this obvious difference is due to inhomogenity of the siltstone texture which causes different behavior in this particular rock.
Hamideh Cheraghi; Behzad Vosoghi
Ali Reza Azmoude Ardalan; Abdorreza Safari; Yahya Tavakkoli
Abstract
The methods applied to regularization of the ill-posed problems can be classified under “direct” and “indirect” methods. Practice has shown that the effects of different regularization techniques on an ill-posed problem are not the same, and as such each ill-posed problem requires its own investigation ...
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The methods applied to regularization of the ill-posed problems can be classified under “direct” and “indirect” methods. Practice has shown that the effects of different regularization techniques on an ill-posed problem are not the same, and as such each ill-posed problem requires its own investigation in order to identify its most suitable regularization method. In the geoid computations without applying Stokes formula, the downward continuation based on Abel-Poisson integral is an inverse problem, which requires regularization. Since so far the regularization of this ill-posed problem has been thoroughly studied, in this paper the regularization of the downward continuation problem based on Abel-Poisson integral, is investigated and various techniques falling into the aforementioned classes of regularizations are applied and their efficiency is compared. From the first class Truncated Singular Value Decomposition (TSVD) and Truncated Generalized Singular Value Decomposition (TGSVD) methods and from the second class Generalized Tikhonov (GT) with the norms and semi-norms in Sobolev subspaces , are applied and their capabilities for the regularization of the problem is compared. Our numerical results derived from simulated studies reveal that the GT method with discretized norm of Sobolev subspace gives the best results among the studied methods for the regularization of the downward continuation problem based on the Abel-Poisson integral. On the contrary, the TGSVD method with the discretized second order derivatives has less consistency with the ill-posed problem and yields less accuracy. Finally, the GT method with discretized norm of Sobolev subspace is applied to the downward continuation of real gravity data of the type modulus of gravity acceleration within the geographical region of Iran to derive a geoid model for this region.
Ahmad Aftabi Sani; Vahid Lotfi
Fereydoun Sabet Ghadam; Vahid Esfahanian; Mohammad Eftekhari Yazdi
Abstract
Capability of the Proper Orthogonal Decomposition (POD) method in extraction of the coherent structures from a spatio-temporal chaotic field is assessed in this paper. As the chaotic field, an ensemble of 40 snapshots, obtained from Direct Numerical Simulation (DNS) of the Kuramoto-Sivashinsky (KS) equation, ...
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Capability of the Proper Orthogonal Decomposition (POD) method in extraction of the coherent structures from a spatio-temporal chaotic field is assessed in this paper. As the chaotic field, an ensemble of 40 snapshots, obtained from Direct Numerical Simulation (DNS) of the Kuramoto-Sivashinsky (KS) equation, has been used. Contrary to the usual methods, where the ergodicity of the field is needed, the ensemble members are generated directly by disturbing the initial conditions in a random fashion. The POD eigenvalues and eigenmodes are extracted, using the POD/SVD technique and an ensemble averaging process is performed on the resulting modes, which are used in reconstruction of the field. The resulted mean field is compared with the Fourier mean field as well as the original (instantaneous) field. The results strictly have shown presence of non-coherent parts in the POD reconstructed field, which can be interpreted as the POD weakness in the filtering of the random part of the field. On the other hand, the ensemble averaged POD modes had obvious superiority, in comparison with the mean Fourier modes, in tracing of the mean behavior of the field and the mean temporal gradients. As a consequence, use of the ensemble averaging in the POD modes can be suggested, at least in some spatio-temporal the fields with dominant coherent structures.
Hossein Afrakhteh; Mahmoud Reza Haghifam
Abstract
In this paper, effect of the islands number variation in restoration process is investigated and a graph based method for determination of optimum islands boundaries is presented. Also, the effect of number and location of black-start units on the restoration process is evaluated. In optimization process, ...
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In this paper, effect of the islands number variation in restoration process is investigated and a graph based method for determination of optimum islands boundaries is presented. Also, the effect of number and location of black-start units on the restoration process is evaluated. In optimization process, objective function is minimizing Energy Not Supplied (ENS) and constraints are voltage margins in buses, transmission lines capacities and generators loading limits. The ENS is evaluated based on generation capacity allocation to demand loads method. Genetic algorithm (GA) is the base of optimization and a suitable chromosome coding is developed to network modeling and applying to the algorithm. In order to assess the capabilities of proposed method, the IEEE-118 bus network has been used as test system and the results of sectionalizing the test system to 2, 3, 4, 5, 6 and 7 islands and the optimum boundaries of each island have been given in case studies section.
Mohammad Kazem Besharati Givi; Amir Sarvari
Abstract
In all engineering applications where solid surfaces slide on each other, friction plays an important role. It becomes even more important, particularly in metal forming processes where the two sliding materials are metallic. Among forming processes, forging is an important process, because of improving ...
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In all engineering applications where solid surfaces slide on each other, friction plays an important role. It becomes even more important, particularly in metal forming processes where the two sliding materials are metallic. Among forming processes, forging is an important process, because of improving material structure, mechanical properties and reducing production time. An inverse analysis technique has been developed to determine the flow stress and friction at the tool/work piece interface simultaneously. The inverse problem is aimed at minimizing the error between experimental data and predictions made by rigid-plastic simulations. The ring compression test was selected for evaluating the method for bulk forming of Aluminum7075. The determined friction data were compared with corresponding data obtained independently using standard calibration curves for cold forging in the ring compression test. Results show that the method discussed in the study is efficient and accurate.
Abolfazl Hassani; Seyyed Hamed Mada'eni
Abstract
Ballast as a part of the railway system plays an important role in the operation of the railways and also has a great impact on repair and maintenance activities. Hence most of the repair and maintenance activities in traditional railway systems are due to the defections in the ballast layer and therefore ...
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Ballast as a part of the railway system plays an important role in the operation of the railways and also has a great impact on repair and maintenance activities. Hence most of the repair and maintenance activities in traditional railway systems are due to the defections in the ballast layer and therefore most of the maintenance budget is spent on repairing these defects. These repair and maintenance activities are usually very costly and time consuming and force the line to be closed for quite a long time. These kinds of problems led to the elimination of the ballast layer and the use of some other elements such as concrete slabs or beam in railways. The results show that the time and money needed for repair and maintenance of concrete slab tracks are much less than ballasted tracks, the technical and economical evaluations also confirm these results. In this paper technical and economical aspects of slab track systems were investigated with the help of national and international experiences and it was concluded that they are competitive solutions to the ballasted tracks in passenger railways.
Ourang Farzaneh; Farajollah Askari
Abstract
In this paper, stability of slopes with a shallow foundation located on top including the shape of the failure mechanism is investigated in static and seismic states. This is a three dimensional problem which is analyzed two dimensionally because 3D analyses are complex and appropriate softwares are ...
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In this paper, stability of slopes with a shallow foundation located on top including the shape of the failure mechanism is investigated in static and seismic states. This is a three dimensional problem which is analyzed two dimensionally because 3D analyses are complex and appropriate softwares are not available.
The conventional method of bearing capacity evaluation of foundations on top of slopes is reviewed and results are compared with those obtained from using a specific three dimensional slope stability algorithm based on upper bound limit analysis theorem.
It is concluded that increasing the foundation load to a threshold level, the effect of the load on the stability of the slopes is negligible, a phenomenon which can not be observed in two dimensional analyses. Determination of this threshold by 3D analyses is a useful criterion for selection of the adequate safety factor in static and seismic slope stability analyses.
Reza Baradaran Kazemzadeh; Seyyed Hesamoddin Zegardi; Mohammad Ali Beheshti Nia
Abstract
This study considers scheduling in Hybrid flow shop environment with unrelated parallel machines for minimizing mean of job's tardiness and mean of job's completion times. This problem does not study in the literature, so far. Flexible flow shop environment is applicable in various industries such as ...
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This study considers scheduling in Hybrid flow shop environment with unrelated parallel machines for minimizing mean of job's tardiness and mean of job's completion times. This problem does not study in the literature, so far. Flexible flow shop environment is applicable in various industries such as wire and spring manufacturing, electronic industries and production lines. After modeling the problem as a mixed integer programming model, three heuristics named Cluster, H1 and H2 is proposed for solving it. The first heuristic (Cluster) algorithm utilizes clustering methods for determining sequence of jobs. The second and third heuristics (H1 and H2) determine sequence of jobs with using SPT and EDD rules, respectively. The experimental results of study show that Cluster algorithm outperforms H1 and H2.
Hassan Monsef; Taher Ghomian
Abstract
There are fewer problems encountered with optical voltage transducers in comparison with their inductive and capacitive counterparts. Although capacitive and inductive transformers are used vastly for the purpose of measurement and protection in the networks, they cause problems such as core saturation ...
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There are fewer problems encountered with optical voltage transducers in comparison with their inductive and capacitive counterparts. Although capacitive and inductive transformers are used vastly for the purpose of measurement and protection in the networks, they cause problems such as core saturation and improper transient responses which decrease the accuracy of measurement and eficiency of the protection schemes. As a result, optical voltage transducers are considered as proper candidates for replacing the conventional inductive and capacitive transformers. Lighter weight, smaller size, larger dynamic range, wider bandwidth, insensitivity to electromagnetic interference, stability over temperature change, absence of iron core saturation, low maintenance and replacement cost, etc. are some of the advantages of optical voltage transducers over inductive and capacitive transformers.
In this paper, the Modified Adaptive Method is introduced in order to measure the integral of electric field with minimum number of sensors. Using this algorithm makes the effects of other fields minimum. One more advantage of this method is the possibility of improving the accuracy of the measurement by using a correction factor. The correction factor is determined by considering the level of accuracy, environmental conditions and the number of sensors. Simulation results show the great validity and effectiveness of this method over a wide range of variations.
Sohrabali Ghorbanian; Ali Reza Salehpour; Sa'eed Reza Radpour
Mohammad Ali Akhavan Behabadi; Hossein Shokouhmand; Masoud Jamali Ashtiani; Amir Mohammadpour
Abstract
The pressure drop of refrigerant R-134a flow boiling inside a horizontal tube has been investigated experimentally. The test set-up which was used in this investigation is a well instrumented vapor compression refrigeration system. These instruments are thermocouples, flow meter, pressure gauges and ...
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The pressure drop of refrigerant R-134a flow boiling inside a horizontal tube has been investigated experimentally. The test set-up which was used in this investigation is a well instrumented vapor compression refrigeration system. These instruments are thermocouples, flow meter, pressure gauges and the pressure drop measuring apparatus. This system consisted of three electrically heated evaporators called as pre-evaporator, test evaporator and after evaporator, respectively. The empirical pressure drop data for two phase flow boiling of R-134a inside a horizontal tube of 7.5mm internal diameter has been collected. The ranges of mass velocities and vapor qualities are 54-136 kg/m2s and 0.2-1, respectively. The collected data were compared with the predicted pressure drop values by seven different correlations. Finally, a new correlation was developed to predict the pressure drop of two phase flow inside evaporators.
Samira Rezaei; Amin Ghodousian
Abstract
In this paper, a mathematical method is proposed to formulate a generalized ordering problem. This model is formed as a linear optimization model in which some variables are binary. The constraints of the problem have been analyzed with the emphasis on the assessment of their importance in the formulation. ...
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In this paper, a mathematical method is proposed to formulate a generalized ordering problem. This model is formed as a linear optimization model in which some variables are binary. The constraints of the problem have been analyzed with the emphasis on the assessment of their importance in the formulation. On the one hand, these constraints enforce conditions on an arbitrary subgraph and then give sufficient conditions for feasibility, on the other hand, they provide a natural way to generalize the applied aspects of the model without increasing the number of the binary variables.
