List of Articles آشوب

• Open Access Article
  • Abstract Page
  • Full-Text
  
  1 - Investigating the Mediating Effect of Organizational Learning Orientation-Performance Relationship under Moderating Market Turbulence (Case Study: Birjand Industrial Park SMEs)
  Morteza Maleki
  According to single-dimensional researches in entrepreneurial orientation-business performance literature and lack of existence for variables contributing more clarity and progress in our understanding, more study is required to be done. The main purpose of this article More

  According to single-dimensional researches in entrepreneurial orientation-business performance literature and lack of existence for variables contributing more clarity and progress in our understanding, more study is required to be done. The main purpose of this article is to investigate the relationship between entrepreneurial orientation and business performance with regard to organizational learning orientation, as a mediator, and market turbulence, as a moderator.  To assess the claim, we collected data by census method from senior managers or/and executives of all 55 active and semi-active SMEs in the Birjand Industrial Park. Findings showed that small firms having high entrepreneurial orientation show more inclination to organizational learning in the turbulent markets, but organizational learning tendency does not necessarily affect positively the performance of small firms even in changing markets. Manuscript profile
• Open Access Article
  • Abstract Page
  • Full-Text
  
  2 - Design of Secure Communication System by Use of Synchronization of Chaotic Systems
  Mohammad nikkhoo masoud shafiee koorosh kiani
  In this paper, the concept of secure synchronization of chaotic systems using adaptive and robust techniques , has been discussed and then a new secure communication scheme, based on secure synchronization of a general class of chaotic systems called Generalized Lorenz More

  In this paper, the concept of secure synchronization of chaotic systems using adaptive and robust techniques , has been discussed and then a new secure communication scheme, based on secure synchronization of a general class of chaotic systems called Generalized Lorenz System, are presented. This communication scheme is combination of conventional cryptographic methods and chaotic modulation method. Analytical and simulation results using sine and voice signal and with unknown constant propagation delay between transmitter and receiver , have been presented. Also, robustness of this scheme against Gaussian channel noise with variance of , and security analysis of this communication system from brute-force viewpoint has been evaluated. By using this communication scheme, the very great key length has been obtained. Manuscript profile
• Open Access Article
  • Abstract Page
  • Full-Text
  
  3 - Modified orthogonal chaotic colonial competition algorithm and its application in improving pattern recognition in multilayer perceptron neural network
  Payman Moallem mehrdad sadeghi hariri MAHDI hashemi
  Despite the success of the Colonial Competition Algorithm (ICA) in solving optimization problems, this algorithm still suffers from repeated entrapment in the local minimum and low convergence speed. In this paper, a new version of this algorithm, called Modified Orthog More

  Despite the success of the Colonial Competition Algorithm (ICA) in solving optimization problems, this algorithm still suffers from repeated entrapment in the local minimum and low convergence speed. In this paper, a new version of this algorithm, called Modified Orthogonal Chaotic Colonial Competition (COICA), is proposed. In the policy of absorbing the proposed version, each colony seeks the space to move towards the colonizer through the definition of a new orthogonal vector. Also, the possibility of selecting powerful empires is defined through the boltzmann distribution function, and the selection operation is performed through the roulette wheel method. The proposed multilevel perceptron neural network (MLP) algorithm is used to classify standard datasets, including ionosphere and sonar. To evaluate the performance of this algorithm and to evaluate the generalizability of the trained neural network with the proposed version, the K-Fold cross-validation method has been used. The results obtained from the simulations confirm the reduction of network training error as well as the improved generalizability of the proposed algorithm. Manuscript profile
• Open Access Article
  • Abstract Page
  • Full-Text
  
  4 - SVD-Based Adaptive Multiuser Detection for Optimized Chaotic DS-CDMA Systems
  S. Shaerbaf S. A. Seyedin
  In recent years, chaotic signals have created a new area in the designation of wideband communication systems. Most of the activity has focused on DS-CDMA systems, in which the conventional pseudo-noise sequences will be replaced by binary chaotic sequences. Unfortunat More

  In recent years, chaotic signals have created a new area in the designation of wideband communication systems. Most of the activity has focused on DS-CDMA systems, in which the conventional pseudo-noise sequences will be replaced by binary chaotic sequences. Unfortunately, despite the advantages of chaotic systems such as aperiodicity, low cost generation and noise-like spectrum, the performance of most of such designs is not still suitable for multiuser wireless channels. In this paper, we propose a novel method based on singular value decomposition for adaptive multiuser detection in chaos-based DS-CDMA systems. We also propose a new genetic algorithm-based method for the optimal generation of chaotic sequences in such systems. Simulation results show that our proposed nonlinear receiver with optimized chaotic sequences outperforms the conventional DS-CDMA systems with “maximal length” codes as well as non-optimized chaos-based DS-CDMA systems in all channel condition, particularly for under-loaded CDMA condition, which the number of active users is less than processing gain. Manuscript profile
• Open Access Article
  • Abstract Page
  • Full-Text
  
  5 - Design of Proportional-Integral Sliding Mode Controllers for Hyperchaotic Systems in the Presence of Uncertainty, Disturbance and Nonlinear Control Inputs
  A. Abooee M. R. Jahed Motlagh Z. Rahmani
  In this paper, robust controllers for a new hyperchaotic system are investigated in the presence of uncertainty, disturbance and nonlinear control inputs. The controllers are designed by considering two major goals: first to stabilize the hyperchaotic system in the pres More

  In this paper, robust controllers for a new hyperchaotic system are investigated in the presence of uncertainty, disturbance and nonlinear control inputs. The controllers are designed by considering two major goals: first to stabilize the hyperchaotic system in the presence of uncertainties, disturbance and nonlinear control inputs; and second, to guarantee the prescribed disturbance attenuation, considering the defined performance index for it. Sliding mode control by defining three proportional integral switching surfaces is used to reach mentioned goals. Numerical simulations are used to exhibit the feasibility and performance of the proposed method. Manuscript profile
• Open Access Article
  • Abstract Page
  • Full-Text
  
  6 - Hyper Spherical Search Optimization Algorithm Based on Chaos Theory
  Mohammad Kalantari S. Sohrabi H. Rashidy Kanan H. Karami
  A Hyper Spherical Search (HSS) optimization algorithm based on chaos theory is proposed that resolves the weakness of the standard HSS optimization algorithm including the speed of convergence and the sequential increment in the number of algorithm iterations to achieve More

  A Hyper Spherical Search (HSS) optimization algorithm based on chaos theory is proposed that resolves the weakness of the standard HSS optimization algorithm including the speed of convergence and the sequential increment in the number of algorithm iterations to achieve the optimal solution. For this, in the particle initiation and search steps of the proposed algorithm, random values used in the standard algorithm are replaced with the values of two mappings, Chebyshev and Liebovitch, that makes the results of the proposed algorithm definite and decreases their standard deviation. The simulation results on the standard benchmark functions show that the proposed algorithm not only has faster convergence, but also acts as a more accurate search algorithm to find the optimal solution in comparison to standard hyper spherical search algorithm and some other optimization algorithms such as genetic, particle swarm, and harmony search algorithm. Manuscript profile