NASHRIYYAH -I MUHANDISI -I BARQ VA MUHANDISI -I KAMPYUTAR -I IRAN, A- MUHANDISI -I BARQ
Year:2005 | Volume:3 | Issue:2|Papers Count:7

In this paper, a method for online recognition of Farsi subwords is presented. First, the dots and other signs of the input subword and their relative locations are recognized and the related group to that subword is chosen. If there is only one member in that group, its class is assigned to the input subword, otherwise, the subword body is compared to those of the group members and the subword with minimum distance to the input subword is found. The recognition system also proposes a maximum of nine subwords in the next ranks. The proposed method was tested on a database of 11 samples of 1000 subwords from different writers. The correct recognition rate for the first choice was 74.95%. It reached to 97.87% for the top 10 choices.

Graphology is the science of study and analysis of the personality of an individual from his/her style of handwriting. In western communities, the most important application of graphology is the recruitment of job applicants. In this regard, computer aided extraction and analysis of features from handwriting can be of great assistance to graphologists. The most dominant features of handwriting employed in graphology include the shape of the page margins, line spacing, line skew, word slant, size of letters, text density, writing speed and regularity. In this paper a number of methods are proposed for automated extraction of some of these features from Farsi handwriting. Experimental results on 118 test samples of different writers are presented and discussed.

In this paper, a method based on learning automata for adaptation of the vigilance factor in Fuzzy ARTMAP network when used for classification problems is proposed. The performance of the proposed algorithm is independent of the initial value for vigilance factor. Fuzzy ARTMAP network in which the vigilance factor adapted using learning automata generates smaller structure with higher recognition rate. To study the performance of the proposed method it has been applied to several problems: circle in square, spirals and square in square problems. The results of experiments show the effectiveness of the proposed method.

Ultra Wideband (UWB) technology has attracted considerable interest in the research and standardization communities, due to its promising ability to provide high data rate at low cost with relatively low power consumption. UWB is characterized by transmitting extremely short duration radio impulses. The signal energy is thus spread over a band of frequencies up to a few GHz. In this paper we outline the attractive features of direct sequence ultra wideband systems employing antipodal signaling (DS_BPSK). First, we compare TH_PPM and DS_UWB in terms of their multiple access performance in AWGN environment. Compared with TH_UWB, results show that DS_UWB supports a larger number of users communicating at higher data rates. Then, we evaluate the multiple access performance of DS_UWB in multipath fading channels. We consider partial Rake receiver structure with different number of Rake fingers. Results show that DS-UWB system using Rake receiver is able to sustain BER less than 10-5 even in channels suffering from severe multipath fading. Using 10 fingers Rake receiver, about 12 dB improvement in performance of system can be achieved.

In this paper a new control scheme is proposed to ensure stability and performance of the teleoperation systems while a wide range of time delay of transmission line is allowed. For this mean, time delay is estimated and used to predict the plant output. A model reference adaptive controller (MRAC) is designed for the master site using the predicted output of the plant. The proposed control system indicates good stability and force tracking performance. For the slave site, an independent MRAC is designed and it is shown that a good tracking for the position and velocity signals is achieved.

Based on Bessel-Thompson filter design method, a new procedure is introduced to determine a desired closed loop characteristic equation for the step input signal. The transient and steady state responses of the calculated system are similar to those of the CDM (Coefficient Diagram Method) controller. Using some properties from Laplace transform, the characteristic equation is then employed to obtain a new closed loop transfer function which results in appropriate response for the ramp input signal. To evaluate the newly defined closed loop transfer function, a RST output feedback controller is designed and simulated.