Showing 15 results for Graph
F.d. Javanroodi , K. M. Nikbin ,
Volume 17, Issue 3 (9-2006)
Abstract
There is an increasing need to assess the service life of components containing defect which operate at high temperature. This paper describes the current fracture mechanics concepts that are employed to predict cracking of engineering materials at high temperatures under static and cyclic loading. The relationship between these concepts and those of high temperature life assessment methods is also discussed. A model for predicting creep crack growth initiation and growth in terms of C* and the creep uniaxial ductility is presented and it is shown that this model gives good agreement with the experimental results. The effects of cyclic loading on crack growth behaviour are considered and fractography evidence is shown to back a simple cumulative damage concept when dealing with creep/fatigue interaction. Finally a discussion is presented which highlights the important aspect of life assessment methodology for high temperature plant.
A. Azaron , S.m. Fatemi Ghomi,
Volume 18, Issue 3 (11-2007)
Abstract
Abstract : In this paper , we apply the stochastic dynamic programming to approximate the mean project completion time in dynamic Markov PERT networks. It is assumed that the activity durations are independent random variables with exponential distributions, but some social and economical problems influence the mean of activity durations. It is also assumed that the social problems evolve in accordance with the independent semi-Markov processes over the planning horizon. By using the stochastic dynamic programming, we find a dynamic path with maximum expected length from the source node to the sink node of the stochastic dynamic network. The expected value of such path can be considered as an approximation for the mean project completion time in the original dynamic PERT network.
Mehdi Alaeiyan,
Volume 19, Issue 1 (3-2008)
Abstract
We call a Clayey graph Γ = Cay(G, S) normal for G, if the right regular representation R(G) of G is normal in the full automorphism group of Aunt(Γ). in this paper, we give a classification of all non-normal Clayey graphs of finite abelian group with valency 6.
Massoud Hadian Dehkordi, Cheraghi Cheraghi,
Volume 19, Issue 1 (3-2008)
Abstract
M. Alaeiyan,
Volume 19, Issue 2 (7-2008)
Abstract
Abstract : We call a Cayley graph Γ = Cay (G, S) normal for G, if the right regular representation R(G) of G is normal in the full automorphism group of Aut(Γ). In this paper, a classification of all non-normal Cayley graphs of finite abelian group with valency 6 was presented.
M. Hadian Dehkordi , A. Cheraghi ,
Volume 19, Issue 2 (7-2008)
Abstract
Abstract : A visual cryptography scheme based on a given graph G is a method to distribute a secret image among the vertices of G, the participants, so that a subset of participants can recover the secret image if they contain an edge of G, by stacking their shares, otherwise they can obtain no information regarding the secret image. In this paper a maximal independent sets of the graph G was applied to propose a lower bound on the pixel expansion of visual cryptography schemes with graph access structure (G ). In addition a lower bound on the pixel expansion of basis matrices C5 and Peterson graph access structure were presented .
S.m. Mohammad Seyedhoseini , M. Ali Hatefi,
Volume 20, Issue 1 (5-2009)
Abstract
Selecting an effective project plan is a significant area in the project management. The present paper introduces a technique to identify the project plan efficient frontier for assessing the alternative project plans and selecting the best plan. The efficient frontier includes two criteria: the project cost and the project time. Besides, the paper presents a scheme to incorporate Directed Acyclic Graph (DAG) into the project risk analysis.
This scheme is used to estimate the expected impacts of the occurrence of the project risks on the project cost and the project time. Also, a theoretical model is defined to provide integration between project risk analysis and overall project planning using the breakdown structures. We believe that applying the proposed technique helps the company’s managers in most effective manner dealing with his complicated project plan assessment and selection problems. The application of the technique was implemented in the companies in construction industry in which represented a considerable cost and time improvements.
Kouroush Jenab, Samir Khoury, Ahmad Sarfaraz,
Volume 23, Issue 1 (3-2012)
Abstract
Evaluative and comparative analysis among educational projects remains an issue for administration, program directors, instructors, and educational institutes. This study reports a fuzzy complexity model for educational projects, which has two primary aspects (technical aspects and transparency aspects). These aspects may not be measured precisely due to uncertain situations. Therefore, a fuzzy graph-based model to measure the relative complexity of educational projects is presented that uses an aggregation operator to resolve conflict among experts with respect to a complexity relation. The model maps the fuzzy graph into a scaled Cartesian diagram that depicts the relative degree of complexity among projects. An illustrative example for several educational projects is demonstrated to present the application of the model.
Yahia Zare Mehrjerdi,
Volume 25, Issue 2 (5-2014)
Abstract
Abstract
Purpose of this paper: The purpose of this article is to review some of the most prominent applications of RFID in industries and to provide a comprehensive review of the work done from 1985 through 2007 and the research trend on that. The effectiveness of RFID and the challenges that it is facing with are also discussed. Some applications of radio frequency identification in supply chain are briefly reviewed and three large cases of radio frequency identification implementation in supply chain are discussed.
Design/methodology/approach: Provides some background on radio frequency identification, and a deep look at the researches conducted from 1985 through 2007. Articles are classified by the year of publications and each case is discussed very briefly. To obtain a good understanding of the level of the researches completed up to the end of 2007 a table and graph are used to demonstrate the summary of results.
Findings: In this research, author came up with 401 articles on RFID as all are listed in a table. The findings point to this fact that research on RFID has started to pick up on year 2002 with 16 publications and then reached to its pick at year 2005 with 112 publications, and then trend went down to 42 and then up to 51 publications for years 2006 and 2007, respectively.
Practical implications (if applicable):
What is original/value of paper: Due to the fact that a better management of a system is related to the full understanding of the technologies implemented, sufficient background on the radio frequency identification technology is provided and the types of researches conducted so far on this matter are briefly discussed.
Ali Mohaghar, Mojtaba Kashef, Ehsan Kashef Khanmohammadi,
Volume 25, Issue 2 (5-2014)
Abstract
Considering the major change occurred in business cells from plant to “chain” and the critical need to choose the best partners to form the supply chain for competing in today’s business setting, one of the vital decisions made at the early steps of constructing a business is supplier selection. Given the fact that the early decisions are inherently strategic and therefore hard and costly to change, it’s been a point of consideration for industries to select the right supplier. It’s clear that different criteria must be investigated and interfered in deciding on the best partner(s) among the alternatives. Thereupon the problem might be regarded as a multiple criteria decision making (MCDM) problem. There are a variety of techniques to solve a MCDM problem. In this paper we propose a novel technique by combination of decision making trial and evaluation laboratory and graph theory and matrix approach techniques. Eventually, the results are compared to SAW technique and discussed to come to a conclusion.
Hossein Mirshojaee, Behrooz Masoumi, Esmaeel Zeinali,
Volume 28, Issue 1 (3-2017)
Abstract
Given the increasing number of documents, sites, online sources, and the users’ desire to quickly access information, automatic textual summarization has caught the attention of many researchers in this field. Researchers have presented different methods for text summarization as well as a useful summary of those texts including relevant document sentences. This study selects extractive method out of different summarizing methods (e.g. abstract method). Extractive method involves summarizing text through objective extraction of some parts of a text like word, sentence, and paragraph. A summarization issue would be unsolvable by exact methods in a reasonable time with considering documents with high amount of information (NP complete). These kinds of issues are usually solved using metaheuristic methods. A biogeography-based optimization algorithm (BBO), which is a new metaheuristic method in the domain of extractive text summarization, is used in this article.
Mosata Setak, Shabnam Izadi, Hamid Tikani,
Volume 28, Issue 4 (11-2017)
Abstract
Logistics planning in disaster response phase involves dispatching commodities such as medical materials, personnel, food, etc. to affected areas as soon as possible to accelerate the relief operations. Since transportation vehicles in disaster situations can be considered as scarce resources, thus, the efficient usage of them is substantially important. In this study, we provide a dynamic vehicle routing model for emergency logistics operations in the occurrence of natural disasters. The aim of the model is to find optimal routes for a fleet of vehicles to give emergency commodities to a set of affected areas by considering the existence of more than one arc between each two nodes in the network (multi-graph network). Proposed model considers FIFO property and focused on minimization of waiting time and total number of vehicles. Various problem instances have been provided to indicate the efficiency of the model. Finally, a brief sensitivity analysis is presented to investigate the impact of different parameters on the obtained solutions.
Fahimeh Tanhaie, Aylin Pakzad,
Volume 34, Issue 2 (6-2023)
Abstract
The capacitated arc routing problem (CARP) is an important vehicle routing problem with numerous real world applications. In this paper, an extended version of CARP, the capacitated arc routing problem with priority edges is presented. The new introduced CARP is more general and closer to reality, and thus is more worthwhile to be solved. In this problem, a set of important priority edges is given and the task is to service of all edges with positive demand in such a way that the higher priority edges are visited as soon as possible. The capacitated arc routing problem with priority edges is an NP-hard problem, so we propose an algorithm that can quickly obtain optimal or near-optimal solution for the defined problem. Another important contribution is that our proposed algorithm is fast and easy to apply. In this paper, through some examples, efficiency of the proposed algorithm has been showed and some guidelines for the future studies have been given
Theodore Alvin Hartanto, Seng Hansun,
Volume 35, Issue 3 (9-2024)
Abstract
One method to diagnose retinal diseases is by using the Optical Coherence Tomography (OCT) scans. Annually, it is estimated that around 30 million OCT scans are performed worldwide. However, the process of analyzing and diagnosing OCT scan results by an ophthalmologist requires a long time so machine learning, especially deep learning, can be utilized to shorten the diagnosis process and speed up the treatment process. In this study, several pre-trained deep learning models are compared, including EfficientNet-B0, ResNet-50V2, Inception-V3, and DenseNet-169. These models will be fine-tuned and trained with a dataset containing OCT scanned images to classify four retinal conditions, namely Choroidal Neovascularization (CNV), Diabetic Macular Edema (DME), Drusen, and Normal. The models that have been trained are then tested to classify the test set and the results are evaluated using a confusion matrix in terms of accuracy, recall, precision, and F1-score. The results show that the model with the best classification results in the batch size of 32 scenario is the ResNet-50V2 model with an accuracy value of 98.24%, precision of 98.25%, recall of 98.24%, and F1-score of 98.24%. While for the batch size of 64, the EfficientNet-B0 model is the model with the best classification results with an accuracy value of 96.59%, precision of 96.84%, recall of 96.59%, and F1-score of 96.59%.
Ahmad Aliyari Boroujeni, Ameneh Khadivar,
Volume 36, Issue 2 (6-2025)
Abstract
The Traveling Salesman Problem (TSP) is a well-known problem in optimization and graph theory, where finding the optimal solution has always been of significant interest. Optimal solutions to TSP can help reduce costs and increase efficiency across various fields. Heuristic algorithms are often employed to solve TSP, as they are more efficient than exact methods due to the complexity and large search space of the problem. In this study, meta-heuristic algorithms such as the Genetic Algorithm and the Teaching-Learning Based Optimization (TLBO) algorithm are used to solve the TSP. Additionally, a discrete mutation phase is introduced to the TLBO algorithm to enhance its performance in solving the TSP. The results indicate that, in testing two specific models of the TSP, the modified TLBO algorithm outperforms both the Genetic Algorithm and the standard TLBO algorithm in terms of convergence to the optimal solution and response time.
