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Issue Info: 
  • Year: 

    2009
  • Volume: 

    9
  • Issue: 

    4
  • Pages: 

    378-383
Measures: 
  • Citations: 

    1
  • Views: 

    262
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2015
  • Volume: 

    1
Measures: 
  • Views: 

    175
  • Downloads: 

    172
Abstract: 

COMMUNITY DETECTION IN SOCIAL NETWORK IS A SIGNIFICANT ISSUE IN THE STUDY OF THE STRUCTURE OF A NETWORK AND UNDERSTANDING ITS CHARACTERISTICS. A COMMUNITY IS A SIGNIFICANT STRUCTURE FORMED BY NODES WITH MORE CONNECTIONS BETWEEN THEM. IN RECENT YEARS, SEVERAL AlgorithmS HAVE BEEN PRESENTED FOR COMMUNITY DETECTION IN SOCIAL NETWORKS AMONG THEM LABEL Propagation Algorithm IS ONE OF THE FASTEST AlgorithmS, BUT DUE TO THE RANDOMNESS OF THE Algorithm ITS PERFORMANCE IS NOT SUITABLE. IN THIS PAPER, WE PROPOSE AN IMPROVED LABEL Propagation Algorithm CALLED MEMORY-BASED LABEL Propagation Algorithm (MLPA) FOR FINDING COMMUNITY STRUCTURE IN SOCIAL NETWORKS. IN THE PROPOSED Algorithm, A SIMPLE MEMORY ELEMENT IS DESIGNED FOR EACH NODE OF GRAPH AND THIS ELEMENT STORE THE MOST FREQUENT COMMON ADOPTION OF LABELS ITERATIVELY. OUR EXPERIMENTS ON THE STANDARD SOCIAL NETWORK DATASETS SHOW A RELATIVE IMPROVEMENT IN COMPARISON WITH OTHER COMMUNITY DETECTION AlgorithmS. ...

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2022
  • Volume: 

    8
Measures: 
  • Views: 

    92
  • Downloads: 

    0
Abstract: 

Social network analysis with large volumes of data and complex communication structures is so difficult and time-consuming. Community detection is one of the major challenges in network analysis. A community is a set of individuals or organizations whose communication density is more than other network entities. Community detection or clustering can reveal the structure of groups in social networks, or relationships between entities. The label Propagation Algorithms with neighbor node influence have less complexity than traditional Algorithms, such as clustering, to recognize communities. Also, the Algorithms can identify overlapping communities. In our label Propagation Algorithm, which is based on the neighbor node influence, important nodes are more likely to publish their labels, while less important nodes have a small chance of spreading the label. The degree of similarity of nodes and the effect of nodes in a social network depends on the parameter of path length between nodes. In the proposed method, increasing this parameter leads to more accurate identification of overlapping and stable communities. The proposed Algorithm detects overlapping communities with the same accuracy as the previous Algorithms with fewer iterations, in less time. The Algorithm is implemented on real and artificial social networks with weightless graphs and weighted graphs with weighting by Jacquard similarity criterion, in all of which the execution time is improved.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2009
  • Volume: 

    11
  • Issue: 

    2
  • Pages: 

    147-160
Measures: 
  • Citations: 

    0
  • Views: 

    433
  • Downloads: 

    268
Abstract: 

The use of neural networks methodology is not as common in the investigation and prediction noise as statistical analysis. The application of artificial neural networks for prediction of power tiller noise is set out in the present paper. The sound pressure signals for noise analysis were obtained in a field experiment using a 13-hp power tiller. During measurement and recording of the sound pressure signals of the power tiller, the engine speeds and gear ratios were varied to cover the most normal range of the power tiller operation in transportation conditions for the asphalt, dirt rural roads, and grassland. Signals recorded in the time domain were converted to the frequency domain with the help of a specially developed Fast Fourier Transform (FFT) program. The narrow band signals were further processed to obtain overall sound pressure levels in A-weighting. Altogether, 48 patterns were generated for training and evaluation of artificial neural networks. Artificial neural networks were designed based on three neurons in the input layer and one neuron in the output layer. The results showed that multi layer perceptron networks with a training Algorithm of back Propagation were best for accurate prediction of power tiller overall noise. The minimum RMSE and R2 for the four-layer perceptron network with a sigmoid activation function, Extended Delta-Bar-Delta (Ext. DBD) learning rule with three neurons in the first hidden layer and two neurons in the second hidden layer, were 0.0198 and 0.992, respectively.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2016
  • Volume: 

    4
  • Issue: 

    1
  • Pages: 

    49-54
Measures: 
  • Citations: 

    1
  • Views: 

    1867
  • Downloads: 

    326
Abstract: 

uspended particles have deleterious effects on human health and one of the reasons why Tehran is effected is its geographically location of air pollution. One of the most important ways to reduce air pollution is to predict the concentration of pollutants. This paper proposed a hybrid method to predict the air pollution in Tehran based on particulate matter less than 10 microns (PM10), and the information and data of Aghdasiyeh Weather Quality Control Station and Mehrabad Weather Station from 2007 to 2013. Generally, 11 inputs have been inserted to the model, to predict the daily concentration of PM10. For this purpose, Artificial Neural Network with Back Propagation (BP) with a middle layer and sigmoid activation function and its hybrid with Genetic Algorithm (BP-GA) were used and ultimately the performance of the proposed method was compared with basic Artificial Neural Networks along with (BP) Based on the criteria of - R2-, RMSE and MAE. The finding shows that BP-GA R2 = 0.54889 has higher accuracy and performance. In addition, it was also found that the results are more accurate for shorter time periods and this is because the large fluctuation of data in long-term returns negative effect on network performance. Also, unregistered data have negative effect on predictions. Microsoft Excel and Matlab 2013 conducted the simulations.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2012
  • Volume: 

    25
  • Issue: 

    3 (TRANSACTIONS A: BASICS)
  • Pages: 

    239-247
Measures: 
  • Citations: 

    0
  • Views: 

    301
  • Downloads: 

    196
Abstract: 

This paper presents an incompressible smoothed particle hydrodynamics (SPH) model to simulate wave Propagation in a free surface flow. The Navier-Stokes equations are solved in a Lagrangian framework using a three-step fractional method. In the first step, a temporary velocity field is provided according to the relevant body forces. This velocity field is renewed in the second step to include the viscosity effects. A Poisson equation is employed in the third step as an alternative for the equation of state in order to evaluate pressure. This Poisson equation considers a trade-off between density and pressure which is utilized in the third step to impose the incompressibility effect. The computations are compared with the experimental as well as numerical data and a good agreement is observed. In order to validate proposed Algorithm, a dam-break problem is solved as a benchmark solution and the computational results are compared with the previous numerical ones.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2016
  • Volume: 

    23
Measures: 
  • Views: 

    181
  • Downloads: 

    116
Abstract: 

SPHINGOSINE KINASES (SPHKS) ARE A GROUP OF IMPORTANT ENZYMES THAT CIRCULATES AT LOW MICROMOLAR CONCENTRATIONS IN MAMMALS. THESE ENZYMES HAVE RECEIVED CONSIDERABLE ATTENTION DUE TO THE ROLES THEY ARE REPUTED TO PLAY IN A BROAD ARRAY OF IMMUNOLOGICAL RESPONSES INCLUDING RHEUMATOID ARTHRITIS1 AND ASTHMA2 AND DIFFERENT TYPE OF CANCERS3. ...

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2017
  • Volume: 

    17
  • Issue: 

    4
  • Pages: 

    168-176
Measures: 
  • Citations: 

    0
  • Views: 

    549
  • Downloads: 

    0
Abstract: 

Accurate investigation of physical phenomena is one of the important challenges in engineering fields.The present study investigates a wet tank in which entrance of water is investigated in three cases.When the water wave moves into a tank, complex flow regimes are created. This complexity is mainly associated with different flow mechanisms during the entrance of water and Propagation of waves at the bottom bed that should be modelled by means of Navier-Stokes equations with free-surface capability and in 3D phase. Due to complexity and time consumption of Navier-Stokes equations modelling, shallow water equations are used with the assumption of hydrostatic pressure. First case is about efflux over a wet bed. Second, water influx from the middle top is investigated and then influx from top edges is modelled. A dimensionless number is introduced for each case based on water velocity, gap length and drop height which shows acceptable domain for appropriate compatibility between results. Finally, results of numerical modelling are compared with Navier-Stokes solutions which are obtained from STAR-CD software. Results show admissible compatibility with each other based on observations and inspections.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

CAO QING | PARRY MARK E.

Issue Info: 
  • Year: 

    2009
  • Volume: 

    47
  • Issue: 

    -
  • Pages: 

    32-41
Measures: 
  • Citations: 

    1
  • Views: 

    192
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

View 192

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Author(s): 

BEYGI H. | MEYBODI M.R.

Journal: 

Scientia Iranica

Issue Info: 
  • Year: 

    2001
  • Volume: 

    8
  • Issue: 

    4 (COMPUTER ENGINEERING)
  • Pages: 

    250-264
Measures: 
  • Citations: 

    0
  • Views: 

    334
  • Downloads: 

    256
Keywords: 
Abstract: 

Back Propagation (BP) Algorithm is a systematic method for training multi-layerneural networks, which, despite many successful applications. also has many drawbacks. For complex problems, back Propagation may requie a long time to train the networks and it is possible that no training occurs at all. Long train in time can be the result of non-optimal parameters. It is not easy to choose an appropriate value for the parameters of a particular problem and the parameters are usually determined by rail and error. If the parameters are not chosen appropriately, slow convergence paralysis and continuous instability can result [1-4]. Moreover, the best values for the parameters at the beginning of training may not be good enough later. In this paper A technique has been incorp rated into BP Algorithm for adaptation of steepness parameter and momentum factor in order to achieve a higher rate of convergence. Through interconnection of Fixed Structure Learn in Automata (FSLA) to the feed forward neural networks. Learning automata scheme is applied in order to adjust these parameters based on the observation of random response of neural networks. The main motivation in using learning automata as an adaptation Algorithm is in is capability of global optimization when dealing with multi-modal surfaces. The feasibility of he proposed method is shown through simulations on three learning problems: exclusive-or encoding problem and digit recognition. These problems are chosen because they have different error surfaces and collectively present an environment that is suitable to determine the effect of the proposed method. The simulation results show that the adaptation of these parameters using his method increases not only the convergence rate of learning but also the likelihood of escaping the local minima. Computer simulations provided in this paper indicate that at least a magnitude of savings in running time can be achieved when FSLA is used for the adaptation of momentum factor and steepness parameters. Furthermore simulations demonstrate that the FSLA approach performs much better than the Variable Structure Learning Automata (VSLA) approach reported in [1,2].

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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