University of Tabriz

About: University of Tabriz is a education organization based out in Tabriz, Iran. It is known for research contribution in the topics: Population & Nanocomposite. The organization has 12141 authors who have published 20976 publications receiving 313982 citations.

Prediction of tractor repair and maintenance costs using Artificial Neural Network

Abstract: The prediction of repair and maintenance costs has significant impacts on proper economical decisions making of machinery managers, such as machine's replacement and substitution. In this article the potential of Artificial Neural Network (ANN) technique has evaluated as an alternative method for the prediction of machinery (specifically tractor) repair and maintenance costs. The study was conducted using empirical data on 60 two-wheel drive tractors from Astan Ghodse Razavi agro-industry in Iran. Optimal parameters for the network were selected via a trial and error procedure on the available data. In this paper, the performance of Basic Back-propagation (BB) training algorithm was also compared with Back-propagation with Declining Learning-Rate Factor algorithm (BDLRF). It was found that BDLRF has a better performance for the prediction of tractor's costs. The prediction of repair and maintenance cost components of tractors with a single network produced a better result than using separate networks for prediction of each cost component. It has been concluded that ANN represents a promising tool for predicting repair and maintenance costs.

A comprehensive review on anticancer mechanisms of the main carotenoid of saffron, crocin.

Abstract: Objectives Crocin is derived from dried stigmas of Crocus sativus L. (saffron). It has long been used to prevent and treat various diseases. Although crocin is suggested as one of the most effective cancer therapeutic constituents of saffron stigma, its exact molecular mechanisms are not fully understood. In this study, we reviewed anticancer effects of crocin and its underlying molecular mechanisms. Key findings While several mechanisms may account for the antitumour activity of crocin, alteration of expression/activity of the genes and also epigenetic changes may be considered as necessary phenomena. These alternations may lead to inhibition of cancer cells' proliferation or/and induction of apoptosis through various mechanism including inhibition of synthesis of DNA and RNA, interaction with cellular topoisomerase, suppression of the telomerase activity and active STAT3, and targeting of microtubules. Moreover, this carotenoid could reverse the epithelial–mesenchymal transition and inhibit metastasis. Conclusions Knowing molecular mechanisms of antitumoral agents could guide us to choose the best chemotherapeutic compound especially for targeted therapy and also provide insights about possible side effects.

Robust adaptive control of a bio-inspired robot manipulator using bat algorithm

Abstract: A new combined control law (AFOPIDSMC) proposed for chattering reduction.We apply an adaptive controller for updating FOPID parameters.A bio-inspired bat algorithm used for tuning the proposed controller parameters.The stability of the proposed controller is proved by Lyapunov theory.The simulation results show the effectiveness of the proposed control. This paper proposes a novel adaptive fractional order PID sliding mode controller (AFOPIDSMC) using a Bat algorithm to control of a Caterpillar robot manipulator. A fractional order PID (FOPID) control is applied to improve both trajectory tracking and robustness. Sliding mode controller (SMC) is one of the control methods which provides high robustness and low tracking error. Using hybridization, a new combined control law is proposed for chattering reduction by means of FOPID controller and high trajectory tracking through using SMC. Then, an adaptive controller design motivated from the SMC is applied for updating FOPID parameters. A metaheuristic approach, the Bat search algorithm based on the echolocation behavior of bats is applied for optimal design of the Caterpillar robot in order to tune the parameter AFOPIDSMC controllers (BA-AFOPIDSMC). To study the effectiveness of Bat algorithm, its performance is compared with five other controllers such as PID, FOPID, SMC, AFOPIDSMC and PSO-AFOPIDSMC. The stability of the AFOPIDSMC controller is proved by Lyapunov theory. Numerical simulation results completely indicate the advantage of BA-AFOPIDSMC for trajectory tracking and chattering reduction.

A novel technique for estimation and control of stator flux of a salient-pole PMSM in DTC method based on MTPF

Abstract: A permanent-magnet synchronous machine (PMSM) can be controlled using the direct torque control (DTC) technique in three different ways, i.e., by controlling flux, reactive torque and rotor d-axis current. Frequently, the DTC technique controls the speed of the motor by controlling stator flux with the aim of obtaining an optimal torque. A varying flux, proportional to the torque, may be used instead of a fixed flux, resulting in a maximum torque per ampere or maximum torque per flux (MTPF). In this paper, a reference-flux-generating method is followed to achieve the MTPF. An approximate equation is then derived using numerical techniques in order to obtain the reference flux from the torque. This equation is then applied to the DTC control system in order to obtain the reference flux. The control scheme has been verified by simulation and tests on a salient-pole permanent-magnet synchronous motor.