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

TEIMOURI M.

Issue Info: 
  • Year: 

    2015
  • Volume: 

    6
  • Issue: 

    1
  • Pages: 

    1-7
Measures: 
  • Citations: 

    0
  • Views: 

    868
  • Downloads: 

    0
Abstract: 

Modulation recognition and symbol duration estimation is the first step towards the exploration of the electromagnetic signals transmitted in electronic battlefields. One of the simplest procedures for blind symbol duration estimation of digitally modulated signals is done by analysis of zero-crossings of the key signal features, which are instantaneous frequency, phase, and amplitude. In this paper, a modified algorithm based on previous works is proposed for estimation of digital modulations symbol duration. The performance of the proposed algorithm is evaluated in the presence of carrier frequency offset and as the simulation results indicate, the performance of the modified algorithm is much better than the classic algorithm. As it is expected and it is shown, the robustness of this method for amplitude or frequency modulation is more than the robustness for phase modulation.

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

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Author(s): 

AALAMI H.A.

Issue Info: 
  • Year: 

    2015
  • Volume: 

    6
  • Issue: 

    1
  • Pages: 

    9-18
Measures: 
  • Citations: 

    0
  • Views: 

    1587
  • Downloads: 

    0
Abstract: 

The improvement in passive defence capabilities of electric power distribution network, especially in the critical sectors like “no power outage” or “fast fault recovery” is highly important. Nowadays, distributed electric power generation (DG) systems especially in military areas are being increasingly used. In the event of an error, if the location of a fault is specified, the possibility of fast resolution of the fault will be enhanced in the network. In a power distribution network which includes some DG systems, conventional methods of fault location will not be accurate and proper. In order to retain system stability, fault location in electric power distribution network has been studied in this paper. The proposed method is based on impedance matrix of distribution network which has high accuracy and speed to fault location and considering not withstanding asymmetry in the network and load; the Simulink results has high accuracy. In this study, all the Simulink designs are performed in open DSS software under different fault conditions and the results have been processed by MATLAB software.

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: 

    6
  • Issue: 

    1
  • Pages: 

    19-32
Measures: 
  • Citations: 

    0
  • Views: 

    1713
  • Downloads: 

    0
Abstract: 

Proper planning and operation of power system as a defence issue, is affected by several factors such as small signal rotor angle stability of generators. This type of stabilities are usually studied in two oscillatory modes including local and inter-area oscillations. Since the study of these events by using conventional methods of stability is difficult, in this paper, index-based participation factor of generators in the dominant mode is introduced and then type and location of the oscillations of power system are predicted by the neural network. In addition, the damping of the critical mode is predicted using neural network. Moreover, capability of the proposed method is evaluated by considering the effect of static load models and noisy data. The proposed method gives appropriate information of power system to the network operators in the normal and emergency conditions with high accuracy and speed.

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

View 1713

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Author(s): 

SAIF M.R. | KHAZAEI S.

Issue Info: 
  • Year: 

    2015
  • Volume: 

    6
  • Issue: 

    1
  • Pages: 

    33-43
Measures: 
  • Citations: 

    0
  • Views: 

    1006
  • Downloads: 

    0
Abstract: 

Investigating the possibility of detection of underground structures is one of the complicated problems. In this paper, making use of gravity gradient data is introduced as an efficient technique to solve this problem. In order to analyze this problem thoroughly and take into account all parts of it, both direct and inverse problems are treated in this contribution. In the direct problem, with the assumption of the known size and position of the structure, gravity gradient signal is modeled. Then, using this modeled signal and by considering the noise level of the gradiometer, some points about the detectability of the structure are discussed. In the inverse problem, position of the underground target is estimated based on the Euler deconvolution, given the gravity gradient tensor. Finally, both of the direct and inverse problems are implemented based on simulated data and some suggestions are made to decrease the probability of detectability of the underground targets.

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

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Author(s): 

NOROZI Z. | MAIMANI H.R.

Issue Info: 
  • Year: 

    2015
  • Volume: 

    6
  • Issue: 

    1
  • Pages: 

    45-54
Measures: 
  • Citations: 

    0
  • Views: 

    879
  • Downloads: 

    0
Abstract: 

One of the important parameters of the secret sharing scheme is information rate, which defines the size of distributed information among the shareholders in comparison of their secret key size. Generally, for any given access structure, it is not possible that one can find the information rate of secret sharing schemes, but finding these rate for some specific designs is possible. In this paper, an upper bound of information rate is presented using independent sequence method, then, the secret sharing schemes whose access structure having five minimal qualified subsets have been investigated and some of the characterizations of ideal secret sharing schemes have been obtained and for the non-ideal case, bounds on the optimal information rate have been provided.

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

View 879

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Issue Info: 
  • Year: 

    2015
  • Volume: 

    6
  • Issue: 

    1
  • Pages: 

    55-64
Measures: 
  • Citations: 

    0
  • Views: 

    720
  • Downloads: 

    0
Abstract: 

The detection of military and civilian targets in the snowy regions by enemy ultraviolet sensors has caused great loss of life and property damage. This research is a way to reduce the enemy’s ultraviolet vision and camouflage of military and civilian targets. For camouflage of these targets in the snowy environments, coatings materials, that have both the visible and ultraviolet reflectance similar to that of snow, should be used. The materials that have high visible and ultraviolet reflectance are usually in the powder form and need to be dispersed in a matrix. In this study, the polyvinylidene fluoride and calcium carbonate were used as a matrix and filler, respectively, to fabricate composite coatings. Assimilating of the spectral behavior of the composite coatings with snow was performed via the identification and optimization of the factors affecting their fabrication. The composite coating was prepared under optimal conditions (PVDF to DMF ratio; 5 %W/W, CaCO3 to PVDF+CaCO3 ratio; 50 %W/W, composite layer drying temperature; 35oC and volume of liquid mixture for the preparation of composite layer; 3ml) and then its reflection spectrum was compared with NATO snow camouflage coatings in both visible and ultraviolet regions. The results showed that the reflection of the produced composite coating is in the range covered by NATO standard snow camouflage coatings, and thus can be used as a camouflage coating to hide the military and civilian targets in the snowy environments.

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: 

    6
  • Issue: 

    1
  • Pages: 

    65-71
Measures: 
  • Citations: 

    0
  • Views: 

    1110
  • Downloads: 

    0
Abstract: 

Packet classification is one of the main processes that often run on network processors. In hardware implementation of packet classification algorithms, Ternary Content Addressable Memories (TCAMs) are used to implement parallel search and process packets rapidly. In classifier architecture, first, decision tree is created and classifier rules are distributed among its leaves. In the second stage, rules are included in different blocks of TCAM corresponding to leaf of the tree structure. In this study, a new dynamic algorithm is offered to select the best bits for cutting in representation of rules in geometric space to distribute them equally and reduce their duplication in the decision tree. Efficiency of the proposed architecture which uses dynamic cuts has been compared with recent architectures. Comparing results shows that the proposed method can distribute rules in TCAM block more balanced than recent architectures. Therefore, memory and power consumption requirements are reduced considerably.

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

View 1110

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