فهرست مطالب

Majlesi Journal of Electrical Engineering - Volume:2 Issue: 4, 2009
  • Volume:2 Issue: 4, 2009
  • 80 صفحه،
  • تاریخ انتشار: 1387/12/20
  • تعداد عناوین: 9
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  • Nafiseh Salehian, Mohamadreza Yazdchi, Alireza Karimian Page 1
    This paper introduces a complete system for recognition of Farsi Nastaaligh handwritten words using Neural Networks. In preprocessing stage, after connected component specification, new algorithms are applied to find and eliminate ascenders, descenders, dots, and other secondary strokes from the original image. Then by using a segmentation algorithm based on analyzing upper and under contours, the word is segmented to a series of sub-words and their arrangement (Right to Left) is defined. Eight features, including three Fourier descriptors and five structural and discrete features, are applied to represent symbols in the feature space. Recognition is based on using a Feed Forward Back Propagation Network. ‏‏The probable mistakes in recognition of sub-words will be corrected by using a search algorithm in dictionary of system. Experiments on a sample of 320 words show a suitable performance (%97 correct recognition) of the system.
  • Ali Zare Page 11
    STATCOM is one of the most popular devices that been used for voltage stability. There has been no report on the effect of SATCOM control mode on voltage stability. It is very important to understand which parameters and what value of these parameters affect the voltage stability. The results of previous studies have shown that the STATCOM have considerable effects on the improvement of voltage stability, but there have not been any investigations on the effects of the control mode of STATCOM on the voltage stability. This paper deals with the effect of the STATCOM control mode on voltage stability. Simulation results on the IEEE 30-bus test system show the high effect of the STATCOM control mode on voltage stability.
  • Negar Ahmadi, Reza Berangi Page 19
    Recently the problem of modulation classification has received much attention in military and commercial applications. Various approaches introduced to solve this problem. Most of these approaches has been based on some special characteristics of received signal which are resolvable for various types of modulations. In this paper modulated signal symbols constellation utilizing TTSAS clustering algorithm and matching with standard templates, is used for classification of QAM modulation. TTSAS algorithm used in this paper is implemented by Hamming neural network. The simulation results show the capability of this method for modulation classification with high accuracy and appropriate convergence in the presence of noise.
  • Mohsen Elyasi Page 27
    The paper investigates the effect of antenna tilting on UMTS network performance. At first radio network planning of UMTS networks based on WCDMA technology is described. Next the dimensioning and detailed planning phases are described. Finally, the effect of antenna tilting on network coverage, capacity and interference is analyzed and based on the results, an optimum tilt angle can be found for different bit rates. All results for different services with 8, 64 and 144 Kbps bit rates are presented.
  • Mohamadreza Nami, Maliheh Kamali, Mahsa Abbasi, Elham Farsi Page 37
    Applying intelligent agents in engineering has become one of novel subjects in implementation of distributed systems. Autonomy, Social Ability, Reactivity and Proactiveness are definitive properties of intelligent agents to improve e-government functionalities. The purpose of this paper is to present an agent-based model for e-government. It categorizes the properties of intelligent agents and proposes a framework for improvement of e-government functionalities. Merging agent-oriented methodologies and self-managing can increase reliability in implementation of complex parts of e-government.
  • Marjan Radi, Behnam Dezfouli, Mohamadali Nematbakhsh Page 43
    In many applications of wireless sensor networks, certain quality of end-to-end parameters is needed. Due to this requirement, supporting quality of service (QoS) in this kind of networks is of great importance. In recent years, multi-path routing technique is proposed as an effective approach to provide QoS. Utilizing multiple paths between senders and receivers, multi-path routing techniques can improve metrics such as reliability, power consumption, delay, throughput, and bandwidth. In this paper, we review the challenges of supporting QoS in wireless sensor networks. In addition, the benefits of multi-path routing are presented. Main elements of multi-path routing protocols are also introduced. At the end, we investigate the design of some multi-path routing protocols and present an application-based categorization of these protocols.
  • Akram Salehpour Page 59
    IEEE 802.11i Sandard have good privacy, integrity and authentication and good management key. However this standard dos not really mention about accessability and protection of management and control frame, so it is vulnerable again DoS attacks and allow a hacker to play different attacks. One type of this threat is due to EAP fames which make heavy traffic on network, and cause blocking server or legal user. In this paper we review attacks due these frames, and we present good way to deal with these attacks.
  • Hanmid Dehghani Page 67
    Endpoint detection, which means distinguishing speech and non-speech segments, is considered as one of the key preprocessing operations in automatic speech recognition (ASR) systems. Usually the energy of speech signal and Zero Crossing Rate (ZCR), are used to locate the beginning and ending for an utterance. Both of these methods have been shown to be effective for endpoint detection. However, especially in a high noise environment they fail. In this paper, we integrate the modified Teager approach with the Energy-Entropy Features. In our new algorithm, the Teager Energy is used to determine crude endpoints, and the Energy-Entropy Features are used to make the final decision. The advantage of this method is that there is no need to estimate the background noise. Therefore, it is very helpful for environments when the beginning or ending noise is very strong or there is not enough “silence” at the beginning or at the end of the utterance. Experimental results on Farsi speech show that the accuracy of this algorithm is quite satisfactory and acceptable for speech endpoints detection.