Sharif Digital Repository

Electromyogram signal (EMG) is an electrical manifestation of contractions of muscles. Surface EMG (sEMG) signal collected form surface of the skin has been used in diverse applications. One of its usages is exploiting it in a pattern recognition system which evaluates and synthesizes hand prosthesis movements. The ability of current prosthesis has been limited in simple opening and closing that decreases the efficacy of these devices in contrary to natural hand. In order to extend the ability and accuracy of prosthesis arm movements and performance, a novel approach for sEMG pattern recognizing system is proposed. In order to have a relevant comparison, present and recent research for... 

Nowadays, reduced switch rectifiers are more interested because of less expense. Control of these rectifiers is an important part of their designing process. In this paper, a method is proposed for four-switch rectifier to continue working under unbalanced input voltage. To achieve this goal, first a method is introduced to separate positive and negative sequences of dq components. Also, the necessary condition is determined. Considering this condition, the control method is modified and new reference value for the control signals is calculated. Finally, the system is simulated in Simulink and the results are provided. These results confirm the accuracy of the developed model, and also the... 

This paper proposes a set of higher-order modified moments for estimation of the fundamental frequency of speech and explores the impact of the speech window length on pitch estimation error. The pitch extraction methods are evaluated in a range of noise types and SNRs. For calculation of errors, pitch reference values are calculated from manually-corrected estimates of the periods obtained from laryngograph signals. The results obtained for the 3 rd and 4 th order modified moment compare well with methods based on correlation and magnitude difference criteria and the YIN method; with improved pitch accuracy and less occurrence of large errors  

The development of a synthetic model of a pregnant woman abdomen with amniotic fluid and a fetus is discussed comprehensively in this paper. The model is intended to be used for studying the light propagation through physical 3D model of pregnant woman in reflectance mode. To construct the model, reported dimension values of body curvature in 26 and 28 weeks of pregnant woman are being used as main references. Although slightly adjustments have been made to the body dimensions, the values are still within the range of reference values. Optical simulation has been performed in order to test the model capability. Given the reasonable computational time and encouraging preliminary results, the... 

Secondary voltage control is used to re-adjust the reference values of automatic voltage regulators of generators. The performance of the secondary voltage control strongly depends on pilot node selection. In this paper the two proposed control laws for secondary voltage control are discussed and then an immune based algorithm is proposed to solve the optimal pilot node selection problem. The proposed algorithm is based on the clonal selection theory. The merit of immune algorithm lies in pattern recognition and memorization capabilities. Also, to provide independency of electrical zones a decoupling factor based on electrical distance concept is proposed. To verify the network observability... 

The aim of this study is to employ feedback control loops to provide a stable forward dynamics simulation of human movement under repeated position constraint conditions in the environment, particularly during stair climbing. A ten-degrees-of-freedom skeletal model containing 18 Hill-type musculotendon actuators per leg was employed to simulate the model in the sagittal plane. The postural tracking and obstacle avoidance were provided by the proportional-integral-derivative controller according to the modulation of the time rate change of the joint kinematics. The stability of the model was maintained by controlling the velocity of the body's centre of mass according to the desired centre of... 

In this research, the main parameters of the multivariate cumulative sum (CUSUM) control chart (the reference value k, the control limit H, the sample size n and the sampling interval h) are determined by minimising the Lorenzen-Vance cost function [Lorenzen, T.J., and Vance, L.C. (1986), The Economic Design of Control Charts: A Unified Approach, Technometrics, 28, 3-10], in which the external costs of employing the chart are added. In addition, the model is statistically constrained to achieve desired in-control and out-of-control average run lengths. The Taguchi loss approach is used to model the problem and a genetic algorithm, for which its main parameters are tuned using the response... 

Background: Studying the kinematics of the ACL deficient (ACLD) knees, during different physiological activities and muscle contraction patterns, can improve our understanding of the joint's altered biomechanics due to ACL deficiency as well as the efficacy and safety of the rehabilitations exercises. Methods: Twenty-five male volunteers, including 11 normal and 14 unilateral ACLD subjects, participated in this study. The kinematics of the injured knees of the ACLD subjects was compared with their intact knees and the healthy group during passive flexion and isometric leg press with the knees flexed from full extension to 45° flexion, with 15° intervals. An accurate registration algorithm... 

The spatiotemporal variability of ambient volatile organic compounds (VOCs) in Tehran, Iran, is not well understood. Here we present the design, methods, and results of the Tehran Study of Exposure Prediction for Environmental Health Research (Tehran SEPEHR) on ambient concentrations of benzene, toluene, ethylbenzene, p-xylene, m-xylene, o-xylene (BTEX), and total BTEX. To date, this is the largest study of its kind in a low- and middle-income country and one of the largest globally. We measured BTEX concentrations at five reference sites and 174 distributed sites identified by a cluster analytic method. Samples were taken over 25 consecutive 2-weeks at five reference sites (to be used for...