List of articles (by subject) Pervasive computing
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Open Access Article
1 - A New Method for Transformation Techniques in Secure Information Systems
Hojatallah HamidiThe transformation technique relies on the comparison of parity values computed in two ways. The fault detection structures are developed and they not only detected subsystem faults but also corrected faults introduced in the data processing system. Concurrent parity va MoreThe transformation technique relies on the comparison of parity values computed in two ways. The fault detection structures are developed and they not only detected subsystem faults but also corrected faults introduced in the data processing system. Concurrent parity values techniques are very useful in detecting numerical error in the data processing operations, where a single fault can propagate to many output faults. Parity values are the most effective tools used to detect faults occurring in the code stream. In this paper, we present a methodology for redundant systems that allows to detect faults. Checkpointing is the typical technique to tolerate such faults. This paper presents a checkpointing approach to operate on encoded data. The advantage of this method is that it is able to achieve very low overhead according to the specific characteristic of an application. The numerical results of the multiple checkpointing technique confirm that the technique is more efficient and reliable by not only distributing the process of checkpointing over groups of processors. This technique has been shown to improve both the reliability of the computation and the performance of the checkpointing. Manuscript profile -
Open Access Article
2 - A New Upper Bound for Free Space Optical Channel Capacity Using a Simple Mathematical in Equality
Arezu Rezazadeh Ghosheh Abed HodtaniIn this paper, by using a simple mathematical inequality, we derive a $ new upper bound fkr the capacity of$ free space optical channel in coherent case. Then, by applying general fading distribution, we obtain an upper bound for mutual information in non-coherent cas MoreIn this paper, by using a simple mathematical inequality, we derive a $ new upper bound fkr the capacity of$ free space optical channel in coherent case. Then, by applying general fading distribution, we obtain an upper bound for mutual information in non-coherent case. Finally, we derive the corresponding optimal input distributions for both coherent and non-coherent cases, compare the results with previous works numerically and illustrate that our results subsume some of previous results in special cases. Manuscript profile -
Open Access Article
3 - Network RAM Based Process Migration for HPC Clusters
Hamid Sharifian msharifi msharifiProcess migration is critical to dynamic balancing of workloads on cluster nodes in any high performance computing cluster to achieve high overall throughput and performance. Most existing process migration mechanisms are however unsuccessful in achieving this goal pr MoreProcess migration is critical to dynamic balancing of workloads on cluster nodes in any high performance computing cluster to achieve high overall throughput and performance. Most existing process migration mechanisms are however unsuccessful in achieving this goal proper because they either allow once-only migration of processes or have complex implementations of address space transfer that degrade process migration performance. We propose a new process migration mechanism for HPC clusters that allows multiple migrations of each process by using the network RAM feature of clusters to transfer the address spaces of processes upon their multiple migrations. We show experimentally that the superiority of our proposed mechanism in attaining higher performance compared to existing comparable mechanisms is due to effective management of residual data dependencies. Manuscript profile -
Open Access Article
4 - Latent Feature Based Recommender System for Learning Materials Using Genetic Algorithm
Mojtaba SalehiWith the explosion of learning materials available on personal learning environments (PLEs) in the recent years, it is difficult for learners to discover the most appropriate materials according to keyword searching method. Recommender systems (RSs) that are used to sup MoreWith the explosion of learning materials available on personal learning environments (PLEs) in the recent years, it is difficult for learners to discover the most appropriate materials according to keyword searching method. Recommender systems (RSs) that are used to support activity of learners in PLE can deliver suitable material to learners. This technology suffers from the cold-start and sparsity problems. On the other hand, in most researches, less attention has been paid to latent features of products. For improving the quality of recommendations and alleviating sparsity problem, this research proposes a latent feature based recommendation approach. Since usually there isn’t adequate information about the observed features of learner and material, latent features are introduced for addressing sparsity problem. First preference matrix (PM) is used to model the interests of learner based on latent features of learning materials in a multidimensional information model. Then, we use genetic algorithm (GA) as a supervised learning task whose fitness function is the mean absolute error (MAE) of the RS. GA optimizes latent features weight for each learner based on his/her historical rating. The method outperforms the previous algorithms on accuracy measures and can alleviate the sparsity problem. The main contributions are optimization of latent features weight using genetic algorithm and alleviating the sparsity problem to improve the quality of recommendation. Manuscript profile -
Open Access Article
5 - A New Finite Field Multiplication Algorithm to Improve Elliptic Curve Cryptosystem Implementations
Abdalhossein Rezai Parviz KeshavarziThis paper presents a new and efficient implementation approach for the elliptic curve cryptosystem (ECC) based on a novel finite field multiplication in GF(2m) and an efficient scalar multiplication algorithm. This new finite field multiplication algorithm performs zer MoreThis paper presents a new and efficient implementation approach for the elliptic curve cryptosystem (ECC) based on a novel finite field multiplication in GF(2m) and an efficient scalar multiplication algorithm. This new finite field multiplication algorithm performs zero chain multiplication and required additions in only one clock cycle instead of several clock cycles. Using modified (limited number of shifts) Barrel shifter; the partial result is also shifted in one clock cycle instead of several clock cycles. Both the canonical recoding technique and the sliding window method are applied to the multiplier to reduce the average number of required clock cycles. In the scalar multiplication algorithm of the proposed implementation approach, the point addition and point doubling operations are computed in parallel. The sliding window method and the signed-digit representation are also used to reduce the average number of point operations. Based on our analysis, the computation cost (the average number of required clock cycles) is effectively reduced in both the proposed finite field multiplication algorithm and the proposed implementation approach of ECC in comparison with other ECC finite field multiplication algorithms and implementation approaches. Manuscript profile -
Open Access Article
6 - Ten Steps for Software Quality Rating Considering ISO/IEC
Hassan Alizadeh Bahram Sadeghi Bigham Hossein AfsariIn software rating area, it is necessary to apply a measurement reference model to evaluate the quality of software. The standard 25030 is an example of an evaluation system which is based on stakeholders' requirements. In this study, an attempt has been made to establi MoreIn software rating area, it is necessary to apply a measurement reference model to evaluate the quality of software. The standard 25030 is an example of an evaluation system which is based on stakeholders' requirements. In this study, an attempt has been made to establish a model in which all implicit and explicit requirements of stakeholders, users and policy makers have been taken into account. In addition, AHP method has been followed to weigh the indicators used in the model. The results show applicability of the model to meet the requirements of Iranian users. Manuscript profile -
Open Access Article
7 - Parameter Estimation in Hysteretic Systems Based on Adaptive Least-Squares
Mansour Peimani Mohammad Javad Yazdanpanah Naser KhajiIn this paper, various identification methods based on least-squares technique to estimate the unknown parameters of structural systems with hysteresis are investigated. The Bouc-Wen model is used to describe the behavior of hysteretic nonlinear systems. The adaptive ve MoreIn this paper, various identification methods based on least-squares technique to estimate the unknown parameters of structural systems with hysteresis are investigated. The Bouc-Wen model is used to describe the behavior of hysteretic nonlinear systems. The adaptive versions are based on the fixed and variable forgetting factor and the optimized version is based on optimized adaptive coefficient matrix. Simulation results show the efficient performance of the proposed technique in identification and tracking of hysteretic structural system parameters compared with other least square based algorithms. Manuscript profile -
Open Access Article
8 - A New Recursive Algorithm for Universal Coding of Integers
Mehdi Nangir Hamid Behroozi Mohammad Reza ArefIn this paper, we aim to encode the set of all positive integers so that the codewords not only be uniquely decodable but also be an instantaneous set of binary sequences. Elias introduces three recursive algorithms for universal coding of positive integers where each c MoreIn this paper, we aim to encode the set of all positive integers so that the codewords not only be uniquely decodable but also be an instantaneous set of binary sequences. Elias introduces three recursive algorithms for universal coding of positive integers where each codeword contains binary representation of the integer plus an attachment portion that gives some information about the first part [1]. On the other hand, Fibonacci coding which is based on Fibonacci numbers is also introduced by Apostolico and Fraenkel for coding of integers [2]. In this paper, we propose a new lossless recursive algorithm for universal coding of positive integers based on both recursive algorithms and Fibonacci coding scheme without using any knowledge about the source statistics [3].The coding schemes which don’t use the source statistics is called universal coding, in these universal coding schemes we should use a universal decoding scheme in the receiver side of communication system. All of these encoding and decoding schemes assign binary streams to positive integers and conversely, without any need of use to probability masses over positive integers. We show that if we use Fibonacci coding in the first part of each codeword we can achieve shorter expected codeword length than Elias Omega code. In addition, our proposed algorithm has low complexity of encoding and decoding procedures. Manuscript profile -
Open Access Article
9 - Joint Relay Selection and Power Allocation in MIMO Cooperative Cognitive Radio Networks
Mehdi Ghamari Adian Hassan AghaeeniaIn this work, the issue of joint relay selection and power allocation in Underlay MIMO Cooperative Cognitive Radio Networks (U-MIMO-CCRN) is addressed. The system consists of a number of secondary users (SUs) in the secondary network and a primary user (PU) in the prima MoreIn this work, the issue of joint relay selection and power allocation in Underlay MIMO Cooperative Cognitive Radio Networks (U-MIMO-CCRN) is addressed. The system consists of a number of secondary users (SUs) in the secondary network and a primary user (PU) in the primary network. We consider the communications in the link between two selected SUs, referred to as the desired link which is enhanced using the cooperation of one of the existing SUs. The core aim of this work is to maximize the achievable data rate in the desired link, using the cooperation of one of the SUs which is chosen opportunistically out of existing SUs. Meanwhile, the interference due to the secondary transmission on the PU should not exceed the tolerable amount. The approach to determine the optimal power allocation, i.e. the optimal transmits covariance and amplification matrices of the SUs, and also the optimal cooperating SU is proposed. Since the proposed optimal approach is a highly complex method, a low complexity approach is further proposed and its performance is evaluated using simulations. The simulation results reveal that the performance loss due to the low complexity approach is only about 14%, while the complexity of the algorithm is greatly reduced. Manuscript profile -
Open Access Article
10 - Fusion of Learning Automata to Optimize Multi-constraint Problem
Sara Motamed Ali AhmadiThis paper aims to introduce an effective classification method of learning for partitioning the data in statistical spaces. The work is based on using multi-constraint partitioning on the stochastic learning automata. Stochastic learning automata with fixed or variable MoreThis paper aims to introduce an effective classification method of learning for partitioning the data in statistical spaces. The work is based on using multi-constraint partitioning on the stochastic learning automata. Stochastic learning automata with fixed or variable structures are a reinforcement learning method. Having no information about optimized operation, such models try to find an answer to a problem. Converging speed in such algorithms in solving different problems and their route to the answer is so that they produce a proper condition if the answer is obtained. However, despite all tricks to prevent the algorithm involvement with local optimal, the algorithms do not perform well for problems with a lot of spread local optimal points and give no good answer. In this paper, the fusion of stochastic learning automata algorithms has been used to solve given problems and provide a centralized control mechanism. Looking at the results, is found that the recommended algorithm for partitioning constraints and finding optimization problems are suitable in terms of time and speed, and given a large number of samples, yield a learning rate of 97.92%. In addition, the test results clearly indicate increased accuracy and significant efficiency of recommended systems compared with single model systems based on different methods of learning automata. Manuscript profile -
Open Access Article
11 - Trust evaluation in unsupervised network: A fuzzy logic approach
Golnar Assadat Afzali Monireh HosseiniBecause of the possibility of anonymity and impersonation in social networks, trust plays an important role in these networks. Pear to pear networks, by eliminating the supervisor roles, besides its benefit in decreasing management costs, have problems in trust and secu MoreBecause of the possibility of anonymity and impersonation in social networks, trust plays an important role in these networks. Pear to pear networks, by eliminating the supervisor roles, besides its benefit in decreasing management costs, have problems in trust and security of users. In this research, by using social networks as supervised networks, trust level of users is evaluated and by identifying these users in unsupervised networks, appropriate trust level is assigned to them. Manuscript profile -
Open Access Article
12 - Blog feed search in Persian Blogosphere
Mohammad Sadegh Zahedi Abolfazl Aleahmad rahgozar rahgozar Farhad OroumchianBlogs are one of the main user generated content on the web. So, it is necessary to present retrieval algorithms to the meet information need of weblog users. The goal of blog feed search is to rank blogs regarding their recurrent relevance to the topic of the query. I MoreBlogs are one of the main user generated content on the web. So, it is necessary to present retrieval algorithms to the meet information need of weblog users. The goal of blog feed search is to rank blogs regarding their recurrent relevance to the topic of the query. In this paper, the state-of-the-art blog retrieval methods are surveyed and then they are evaluated and compared in Persian blogosphere. Also, one of the best retrieval models is optimized by using data fusion methods. Evaluation of the proposed algorithm is carried out based on a standard Persian weblogs dataset with 45 diverse queries. Our comparisons show considerable improvement over existing blog retrieval algorithms. Manuscript profile -
Open Access Article
13 - Selecting Enterprise Resource Planning System Using Fuzzy Analytic Hierarchy Process Approach
hojatallah hamidiTo select an enterprise resource planning (ERP) system is time consuming due to the resource constraints, the software complexity, and the different of alternatives. A comprehensively systematic selection policy for ERP system is very important to the success of ERP pro MoreTo select an enterprise resource planning (ERP) system is time consuming due to the resource constraints, the software complexity, and the different of alternatives. A comprehensively systematic selection policy for ERP system is very important to the success of ERP project. In this paper, we propose a fuzzy analytic hierarchy process (FAHP) method to evaluate the alternatives of ERP system. The selection criteria of ERP system are numerous and fuzzy, so how to select an adequate ERP system is crucial in the early phase of an ERP project. The framework decomposes ERP system selection into four main factors. The goal of this paper is to select the best alternative that meets the requirements with respect to product factors, system factors, management factors and vendor factors. The sub-attributes (sub-factors) related to ERP selection have been classified into thirteen main categories of Functionality, Reliability , Usability , Efficiency , Maintainability , Portability , Cost, Implementation time, User friendliness , Flexibility , Vendor Reputation , Consultancy Services, and R&D Capability and arranged in a hierarchy structure. These criteria and factors are weighted and prioritized and finally a framework is provided for ERP selection with the fuzzy AHP method. Also, a real case study from Iran (PARDIS-LO Company) is also presented to demonstrate efficiency of this method in practice. Manuscript profile -
Open Access Article
14 - An Effective Risk Computation Metric for Android Malware Detection
Mahmood Deypir Ehsan SharifiAndroid has been targeted by malware developers since it has emerged as widest used operating system for smartphones and mobile devices. Android security mainly relies on user decisions regarding to installing applications (apps) by approving their requested permissions MoreAndroid has been targeted by malware developers since it has emerged as widest used operating system for smartphones and mobile devices. Android security mainly relies on user decisions regarding to installing applications (apps) by approving their requested permissions. Therefore, a systematic user assistance mechanism for making appropriate decisions can significantly improve the security of Android based devices by preventing malicious apps installation. However, the criticality of permissions and the security risk values of apps are not well determined for users in order to make correct decisions. In this study, a new metric is introduced for effective risk computation of untrusted apps based on their required permissions. The metric leverages both frequency of permission usage in malwares and rarity of them in normal apps. Based on the proposed metric, an algorithm is developed and implemented for identifying critical permissions and effective risk computation. The proposed solution can be directly used by the mobile owners to make better decisions or by Android markets to filter out suspicious apps for further examination. Empirical evaluations on real malicious and normal app samples show that the proposed metric has high malware detection rate and is superior to recently proposed risk score measurements. Moreover, it has good performance on unseen apps in term of security risk computation. Manuscript profile -
Open Access Article
15 - Effective solving the One-Two Gap Problem in the PageRank algorithm
Javad Paksima Homa KhajehOne of the criteria for search engines to determine the popularity of pages is an analysis of links in the web graph, and various methods have already been presented in this regard. The PageRank algorithm is the oldest web page ranking methods based on web graph and is MoreOne of the criteria for search engines to determine the popularity of pages is an analysis of links in the web graph, and various methods have already been presented in this regard. The PageRank algorithm is the oldest web page ranking methods based on web graph and is still used as one of the important factors of web pages on Google. Since the invention of this method, several bugs have been published and solutions have been proposed to correct them. The most important problem that is most noticed is pages without an out link or so-called suspended pages. In web graph analysis, we noticed another problem that occurs on some pages at the out degree of one, and the problem is that under conditions, the linked page score is more than the home page. This problem can generate unrealistic scores for pages, and the link chain can invalidate the web graph. In this paper, this problem has been investigated under the title "One-Two Gap", and a solution has been proposed to it. Experimental results show that fixing of the One-Two gap problem using the proposed solution. Test standard benchmark dataset, TREC2003, is applied to evaluate the proposed method. The experimental results show that our proposed method outperforms PageRank method theoretically and experimentally in the term of precision, accuracy, and sensitivity with such criteria as PD, P@n, NDCG@n, MAP, and Recall. Manuscript profile -
Open Access Article
16 - A Novel User-Centric Method for Graph Summarization Based on Syntactical and Semantical Attributes
Nosratali Ashrafi Payaman Mohammadreza KangavariIn this paper, we proposed an interactive knowledge-based method for graph summarization. Due to the interactive nature of this method, the user can decide to stop or continue summarization process at any step based on the summary graph. The proposed method is a general MoreIn this paper, we proposed an interactive knowledge-based method for graph summarization. Due to the interactive nature of this method, the user can decide to stop or continue summarization process at any step based on the summary graph. The proposed method is a general one that covers three kinds of graph summarization called structural, attribute-based, and structural/attribute-based summarization. In summarization based on both structure and vertex attributes, the contributions of syntactical and semantical attributes, as well as the importance degrees of attributes are variable and could be specified by the user. We also proposed a new criterion based on density and entropy to assess the quality of a hybrid summary. For the purpose of evaluation, we generated a synthetic graph with 1000 nodes and 2500 edges and extracted the overall features of the graph using the Gephi tool and a developed application in Java. Finally, we generated summaries of different sizes and values for the structure contribution (α parameter). We calculated the values of density and entropy for each summary to assess their qualities based on the proposed criterion. The experimental results show that the proposed criterion causes to generate a summary with better quality. Manuscript profile