Estimation of load torque in induction motors via dynamic sliding mode control and new nonlinear state observer

Ali Karami-Mollaee,Hamed Tirandaz 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.5

This study conducts load torque estimation in an induction motor (IM) with uncertainty using a dynamic sliding mode controller (DSMC) that suppresses chattering using an integrator or a low-pass filter placed before the control signal of the system. Hence, the dimension of the augmented system in DSMC is larger than the dimension of the original system, thus leading to an increase in the number of system states. These new state variables should be determined to control such a system. To address this problem, a new nonlinear state observer (NSO) is suggested and utilized in this study. The proposed method is independent of the uncertainty bound of the system, but the system output must be accessible. These subjects are important in practical implementations. Lyapunov theory is applied to validate the stability of the proposed DSMC and NSO methods. Then, the boundedness of the closed-loop signals is concluded from the stability of the proposed techniques. The validity of the proposed approach is evaluated using an IM model. By using DSMC and NSO, we can simultaneously control the IM and estimate its load torque. In particular, the external bounded load torque signal is compensated by the input control signal of the motor. Simulation results illustrate the advantages of the proposed approach.

Adaptive Fuzzy Fault Tolerant Control Using Dynamic Sliding Mode

Ali Karami-Mollaee,Hamed Tirandaz 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.1

In this paper, an actuator fault tolerant control (FTC) has been designed using dynamic sliding mode control (DSMC) for single input nonlinear systems which are affected from uncertainty. In DSMC the switching of input control signal is removed due to the integrator which is placed before the input control signal of the plant hence, its result is reducing of chattering. However, in DSMC the augmented system (the system plus the integrator) is one dimension bigger than the actual system and then, the plant model should be completely known. To overcome on this problem, an adaptive fuzzy observer (AFO) has been proposed. Finally, we show the combination result of DSMC and AFO is the compensation of the fault by input control signal of the plant, while the performance and robustness of the closed loop system are reserved. The main property of the proposed approach is its simplicity and we only use system output for FTC and moreover, the fault diagnosis (detection, isolation and reconstruction) is done at the same time. The upper bound of the uncertainty is not used in DSMC and AFO, which is important in practical implementation. Simulation results show the advantages of the proposed approach.

Adaptive Nonsingular Integral-type Second Order Terminal Sliding Mode Tracking Controller for Uncertain Nonlinear Systems

Saleh Mobayen,Hamede Karami,Afef Fekih 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.4

Achieving accurate and reliable tracking control for nonlinear systems with uncertainties and disturbances is one of the most challenging problems in nonlinear control. In this paper, we propose an adaptive nonsingular integral-type second order terminal sliding mode tracking control for nonlinear systems with uncertainties. First an integral type sliding manifold is defined to ensure finite time tracking convergence. Then an adaptation mechanism is proposed to estimate the unknown uncertainty upper bound. Finally, the adaptive nonsingular integral-type second order terminal sliding mode controller is synthesized without any assumptions about the uncertainties. System stability is proven using the Lyapunov stability theorem. Its performance is assessed using a thruster system and an inverted pendulum. Chattering attenuation, finite time convergence and disturbance mitigation are among the positive features of the proposed approach. Additionally, eliminating the need for the upper bound knowledge resulted in a design that can practically be implemented to a wide range of applications.

Purse-String Versus Linear Conventional Skin Wound Closure of an Ileostomy: A Randomized Clinical Trial

Mina Alvandipour,Babak Gharedaghi,Hamed Khodabakhsh,Mohammad Yasin Karami 대한대장항문학회 2016 Annals of Coloproctolgy Vol.32 No.4

Purpose: Infection is one of the most frequent complications that can occur after ileostomy closure. The incidence of wound infection depends on the skin closure technique, but there is no agreement on the perfect closure method for an ileostomy wound. The aim of this study was to evaluate the incidence of infection, the patient’s approval, and the patient’s pain between purse-string closure (PSC) and the usual linear closure (LC) of a stoma wound. Methods: This randomized clinical trial enrolled 66 patients who underwent a stoma closure from February 2015 to May 2015 in Sari Emam Khomeini Hospital. Patients were divided into 2 groups according to the stoma closing method: the PSC group (n = 34) and the LC group (n = 32). The incidences of infection for the 2 groups were compared, and the patients’ satisfaction and pain with the stoma were determined by using a questionnaire. Results: Infection occurred in 1 of 34 PSC patients (2.9%) and in 7 of 32 LC patients (21.8%), and this difference was statistically significant (P = 0.021). Patients in the PSC group were more satisfied with the resulting wound scar and its cosmetic appearance at one month and three months after surgery (P = 0.043). Conclusion: After stoma closure, PSC was associated with a significantly lower incidence of wound infection and greater patient satisfaction compared to LC. However, the healing period for patients who underwent PSC was longer than it was for those who underwent LC.

Prediction of Water Quality Parameters Using ANFIS Optimized by Intelligence Algorithms (Case Study: Gorganrud River)

Armin Azad,Hojat Karami,Saeed Farzin,Amir Saeedian,Hamed Kashi,Fatemeh Sayyahi 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.7

Water quality management and control has high importance in planning and developing of water resources. This study investigatedapplication of Genetic Algorithm (GA), Ant Colony Optimization for Continuous Domains (ACOR) and Differential Evolution (DE)in improving the performance of adaptive neuro-fuzzy inference system (ANFIS), for evaluating the quality parameters ofGorganroud River water, such as Electrical Conductivity (EC), Sodium Absorption Ratio (SAR) and Total Hardness (TH). Accordingly, initially most suitable inputs were estimated for every model using sensitivity analysis and then all of the qualityparameters were predicted using mentioned models. Investigations showed that for predicting EC and TH in test stage, ANFIS-DEwith R2 values of 0.98 and 0.97, respectively and RMSE values of 73.03 and 49.55 and also MAPE values of 5.16 and 9.55,respectively were the most appropriate models. Also, ANFIS-DE and ANFIS-GA models had the best performance in prediction ofSAR (R2 = 0.95, 0.91; RMSE = 0.43, 0.37 and MAPE = 13.43, 13.72) in test stage. It is noteworthy that ANFIS showed the bestperformance in prediction of all mentioned water quality parameters in training stage. The results indicated the ability of mentionedalgorithms in improving the accuracy of ANFIS for predicting the quality parameters of river water.

Incidentally Solitary, Synchronous, Metastatic Left Adrenal Mass From Colon Cancer

Mina Alvandipour,Mohammad Yasin Karami,Mehdi Khalvati,Hamed Khodabakhsh 대한대장항문학회 2016 Annals of Coloproctolgy Vol.32 No.2

The authors report the case of a 63-year-old man who underwent an open adrenalectomy for a synchronous, malignant, metastatic left adrenal tumor and a total colectomy for T3N0M1 (stage 4) primary, malignant colon cancer. Two polypoid lesions, one measuring 40 mm × 30 mm × 30 mm and the other measuring 20 mm × 10 mm × 10 mm, were found in the ascending colon and rectosigmoid (RS) junction, respectively, and a synchronous, malignant, left adrenal gland lesion measuring 70 mm × 50 mm × 30 mm was incidentally found on abdominal computed tomography scan. Histological examination revealed a metastatic, necrotic adenocarcinoma of the left adrenal mass, an adenocarcinoma of the cecal mass, and an adenomatous polyp (tubulovillous type) of the smallest polypoid lesion in RS junction that had invaded deeply into the submucosal layer. The patient recovered uneventfully, and his condition is now stable, with no evidence of local recurrence or metastatic disease, 2 years after the surgery. To the best of our knowledge, only 25 cases of an adrenalectomy for treating metastatic adrenal gland tumors have been reported to date; physicians should be aware of the possibility of this event.

Elastic wave propagation analysis in sandwich nanoplate assuming size effects

Amir Behshad,Maryam Shokravi,Akbar Shafiei Alavijeh,Hamed Karami 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.47 No.1

This paper presents a study on the wave propagation of functionally graded material (FGM) sandwich nanoplates with soft core resting on a Winkler foundation. The structure is modelled by classical theory. Motion equations are derived by the assumption of nonlocal Eringen theory and energy method. Then, the equations are solved using an exact method for finding phase velocity responses. The effects of Winkler foundation, nonlocal parameters, thickness and mode number on the dispersion of elastic waves are shown. With the increase of spring constant, the speed of wave propagation increases and reaches a uniform state at a higher wave number.

Effects of Smoking on Cost of Hospitalization and Length of Stay among Patients with Lung Cancer in Iran: a Hospital-Based Study

Sari, Ali Akbari,Rezaei, Satar,Arab, Mohammad,Majdzadeh, Reza,Matin, Behzad Karami,Zandian, Hamed Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.9

Background: Smoking is recognized as a main leading preventable cause of mortality and morbidity worldwide. It is responsible for a considerable financial burden both on the health system and in society. This study aimed to examine the effect of smoking on cost of hospitalization and length of stay (LoS) among patients with lung cancer in Iran in 2014. Materials and Methods: A total of 415 patients were included in the study. Data on age, sex, insurance status, type of hospitals, type of insurance, geographic local, length of stay and cost of hospitalization was extracted by medical records and smoking status was obtained from a telephone survey. To compare cost of hospitalization and LoS for different smoking groups, current smokers, former smokers, and never smokers, a gamma regression model and zero-truncated poisson regression were used, respectively. Results: Compared with never smokers, current and former smokers showed a 48% and 35% increase in hospitalization costs, respectively. Also, hospital LoS for current and former smokers was 72% and 31% higher than for never smokers, respectively. Conclusions: Our study indicated that cigarette smoking imposes a significant financial burden on hospitals in Iran. It is, however, recommended that more research should be done to implement and evaluate hospital based smoking cessation interventions to better increase cessation rates in these settings.