Intelligent fuzzy back-stepping observer design based induction motor robust nonlinear sensorless control

Introduction. The control algorithm of Induction Motor (IM) is massively dependent on its parameters; so, any variation in these parameters (especially in rotor resistance) gives unavoidably error propagates. To avoid this problem, researches give more than solution, they have proposed Variable Structure Control (VSC), adaptive observers such as Model Reference Adaptive System, Extended Luenberger Observer (ELO) and the Extended Kalman Filter (EKF), these solutions reduce the estimated errors in flux and speed. As novelty in this paper, the model speed observer uses the estimated currents and voltages as state variables; we develop this one by an error feedback corrector. The Indirect Rotor Field Oriented Control (IRFOC) uses the correct observed value of speed; in our research, we improve the observer’s labour by using back-stepping Sliding Mode (SM) control. Purpose. To generate the pulse-width modulation inverter pulses which reduce the error due of parameters variations in very fast way. Methods. We develop for reach this goal an exploration of two different linear observers used for a high performance VSC IM drive that is robust against speed and load torque variations. Firstly, we present a three levels inverter chosen to supply the IM; we present its modelling and method of control, ending by an experiment platform to show its output signal. A block diagram of IRFOC was presented; we analyse with mathematic equations the deferent stages of modelling, showed clearly the decoupling theory and the sensorless technique of control. The study described two kinds of observers, ELO and EKF, to estimate IM speed and torque. By the next of that, we optimize the step response using the fuzzy logic, which helps the system to generate the PI controller gains. Both of the two observers are forward by SM current controller, the convergence of SM-ELO and SM-EKF structures is guaranteed by minimizing the error between actual and observed currents to zero. Results. Several results are given to show the effectiveness of proposed schemes.Вступ. Алгоритм керування асинхронним двигуном (АД) багато в чому залежить від його параметрів; тому будь-яка зміна цих параметрів (особливо опору ротора) неминуче призводить до поширення помилок. Щоб уникнути цієї проблеми, дослідники пропонують щось більше, ніж просто рішення: вони запропонували управління змінною структурою (VSC), адаптивні спостерігачі, такі як адаптивна система еталонної моделі, розширений спостерігач Люенбергера (ELO) та розширений фільтр Калмана (EKF); ці рішення зменшують передбачувані помилки за потоком та швидкістю. Новизною цієї статті є те, що спостерігач швидкості моделі використовує оцінені струми та напруги як змінні стани; ми розробляємо його за допомогою коректора зворотного зв'язку помилки. Непряме управління з полю ротора (IRFOC) використовує правильне значення швидкості; у нашому дослідженні ми покращуємо роботу спостерігача, використовуючи керування ковзним режимом (SM) зі зворотним кроком. Мета. Генерувати імпульси інвертора широтно-імпульсної модуляції, які швидко зменшують помилку, викликану змінами параметрів. Методи. Для досягнення цієї мети ми розробляємо дослідження двох різних лінійних спостерігачів, що використовуються для високопродуктивного приводу VSC АД, стійкого до змін швидкості та моменту навантаження. По-перше, ми представляємо трирівневий інвертор, вибраний для живлення АД; ми представляємо його моделювання та метод управління, закінчуючи експериментальною платформою, що демонструє його вихідний сигнал. Представлена блок-схема IRFOC; ми аналізуємо за допомогою математичних рівнянь різні етапи моделювання, наочно демонструючи теорію розв'язки та безсенсорний метод керування. У дослідженні описані два типи спостерігачів, ELO та EKF, для оцінки швидкості та крутного моменту АД. Далі ми оптимізуємо перехідну реакцію, використовуючи нечітку логіку, яка допомагає системі генерувати коефіцієнти посилення ПІ-регулятора. Обидва з двох спостерігачів передаються контролером струму SM, зближення структур SM-ELO та SM-EKF гарантується за рахунок зведення до нуля помилки між фактичним та спостережуваним струмами. Результати. Наведено результати, що показують ефективність запропонованих схем

Smart current control of the wind energy conversion system based permanent magnet synchronous generator using predictive and hysteresis model

Introduction. Given the increasing demand for performance and efficiency of converters and power drives, the development of new control systems must take into account the real nature of these types of systems. Converters and dimmers power are nonlinear systems of a hybrid nature, including elements linear and nonlinear and a finite number of switching devices. Signals input for power converters are discrete signals that control the ‘opening and closing’ transitions of each component. Problem. In the multilevel inverters connected to grid, the switching frequency is the principal cause of harmonics and switching losses, which by nature, reduces the inverter’s efficiency. Purpose. For guarantee the satisfying quality of power transmitted to the electrical grid, while ensuring reduction of current ripples and output voltage harmonics. Novelty. This work proposes a new smart control, based on a predictive current control of the three level neutral point clamped inverter, used in Wind Energy Conversion System (WECS) connected to grid, based permanent magnet synchronous generator, powered by a hysteresis current control for the rectifier. This new formula guarantees handling with the influence of harmonics disturbances (similar current total harmonic distortion), voltage stress, switching losses, rise time, over or undershoot and settling time in WECS. Methods. The basic idea of this control is to choose the best switching state, of the power switches, which ameliorates the quality function, selected from order predictive current control of WECS. Results. Practical value. Several advantages in this intelligent method, such as the fast dynamic answer, the easy implementation of nonlinearities and it requires fewer calculations to choose the best switching state. In addition, an innovative algorithm is proposed to adjust the current ripples and output voltage harmonics of the WECS. The performances of the system were analyzed by simulation using MATLAB/Simulink.Вступ. Зважаючи на зростаючі вимоги до продуктивності та ефективності перетворювачів та силових приводів, при розробці нових систем керування необхідно враховувати реальну природу систем такого типу. Перетворювачі та регулятори потужності являють собою нелінійні системи гібридної природи, що включають лінійні та нелінійні елементи та кінцеве число комутаційних пристроїв. Вхідні сигнали для силових перетворювачів є дискретними сигналами, які керують переходами «відкриття та закриття» кожного компонента. Проблема. У багаторівневих інверторах, підключених до мережі, частота перемикання є основною причиною гармонік та втрат перемикання, що за своєю природою знижує ефективність інвертора. Мета. Гарантувати задовільну якість електроенергії, що передається в електричну мережу, при одночасному зниженні пульсацій струму та гармонік вихідної напруги. Новизна. У цій роботі пропонується новий інтелектуальний контроль, заснований на прогнозуючому керуванні струмом трирівневого інвертора з фіксованою нейтральною точкою, що використовується в системі перетворення енергії вітру (WECS), підключеної до мережі, на основі синхронного генератора з постійними магнітами, що живиться від керування струмом . Ця нова формула гарантує обробку з урахуванням впливу гармонічних перешкод (аналогічні загальні гармонічні спотворення струму), перенапруги, втрат перемикання, часу наростання, пере- чи недорегулювання, а також часу стабілізації WECS. Методи. Основна ідея цього управління полягає у виборі найкращого стану перемикання силових перемикачів, що покращує функцію якості, обрану з порядку прогнозуючого керування струмом WECS. Результати. Практична цінність. Цей інтелектуальний метод має кілька переваг, таких як швидка динамічна відповідь, простота реалізації нелінійностей і необхідність меншої кількості обчислень для вибору найкращого стану перемикання. Крім того, запропоновано інноваційний алгоритм регулювання пульсацій струму та гармонік вихідної напруги WECS. Характеристики системи проаналізовано шляхом моделювання з використанням MATLAB/Simulink

Nerium oleander L. as a Phytoremediation of Heavy Metals in Diyala Governorate – Iraq

The study samples were collected during the months of April and May 2022, samples were collected from different regions in Diyala Governorate – Iraq. The study aimed to assess the role of oleander plant in the phytoremediation  of heavy metals (lead , cadmium , arsenic and selenium)  within Diyala Governorate by estimating their concentration in the leaves of the plant and the soil on which it grows as well as calculating the bioaccumulation factor (BAF). Al-Muqdadiyah Industrial area was one of the most polluted areas with lead,  the highest concentration of lead appeared in the leaves of the oleander plant grown in this area, as well as the soil on which it grows (2.452 and 0.904 ) ppm respectively. The highest concentration of cadmium was recorded for oleander leaves in the old city of Baqubah (2.208ppm), while the highest concentration appeared in the soil on which it grows in the Al-Muqdadiyah Industrial area (0.363ppm). The Al-Muqdadiya industrial area also recorded the highest concentration of arsenic in the leaves of the oleander plant ( 0.559 ppm) ,but the highest concentration in the soil on which it grows was in the central city of Al-Muqdadiyah (0.218ppm) , followed by the industrial city off Al-Muqdadiyah.( 0.132ppm) . The highest concentration of selenium appeared in the industrial city of Al-Muqdadiya in both the leaves of the oleander plant and the soil on which it grows (0.441 and 0.104) ppm. The value of the bioaccumulation factor (BAF) shows the efficiency of the oleander plant in the phytoremediation of cadmium, followed by lead, arsenic and selenium in varying proportions. Keywords : Phytoremediation , Neium oleander , Heavy metals DOI: 10.7176/JEES/12-9-04 Publication date:September 30th 202

Experimental investigation in improving thermal performance of passive heat removal system using mist assisted evaporative cooling

Demands to increase the safety and reliability of the modern nuclear reactors are constantly being made. Typical demands include the increases the thermal performance of the passive heat removal system PHRS by removing larger amounts of energy and applied a technique that leads to reduce size and weight of the PHRS unit. This article presents an experimental investigation on the natural convection based on alternative cooling approach using water mist. The results obtained from the related experimental work indicated that the heat transfer rate was enhanced over that for the airflow as a result of water mist evaporation on the surface of the tubes. The Nu number increases by about 148%, 144%, and 128% respectively for all tube rows compared with airflow. The experimental results of the thermal performance factor values obtained by suspended water mist were correlated as functions of Rayleigh number (Ra) and Weber number (We). Subsequently, the predicted thermal performance factor from the correlation was plotted to compare with the experimental data. It was found that the thermal performance factor was within ±11%. © 2020 PENERBIT AKADEMIA BARU

Unsteady forced convection heat transfer of a stationary and rotating sphere: Experimental Investigation

Unsteady forced convection heat transfer of a stationary and rotating sphere in an open-loop air system was experimentally investigated with an aim to evaluate the influence of sphere rotation rate on the heat transfer enhancement. A special-purpose conical diffuser having a circular cross-section with constant divergence angle has been carefully designed and adopted as a passive rotating technique. The effect of inlet Re number, non-dimensional rotational speed, and initial surface temperature on heat transfer enhancement are examined. It is observed from the comparison made that there are significant differences between the stationary and rotating sphere of heat transfer behavior. The experimental results of heat transfer behavior in terms of heat flux q and Nusselt number Nu, respectively, expose that q decreases with increase of non-dimensional rotational speed, while Nu increases with the increase of non-dimensional rotational speed around 600%. © Published under licence by IOP Publishing Ltd

Key role of MIF-related neuroinflammation in neurodegeneration and cognitive impairment in Alzheimer's disease.

Macrophage Migration Inhibitory Factor (MIF) is a potent proinflammatory cytokine that promotes the production of other immune mediators. MIF is produced by most cell types in the brain including microglia, astrocytes and neurons. Enhanced expression of MIF might contribute to the persistent activation of glial, chronic neuroinflammation and neurodegeneration. Here, we investigated the effect of MIF on inflammatory markers and spatial learning in a mouse model of sporadic AD and on tau pathology in AD patients. We examined the effects of MIF deficiency and pharmacological MIF inhibition in vitro and in vivo. In vitro, quantitative PCR and ELISA were used to assess cytokine production of STZ-treated glial cells. In vivo, C57BL/6 mice were subjected to intracerebroventricular streptozotocin injection (3 mg/kg, ICV-STZ). Neuroinflammation and contextual learning performance were assessed using quantitative PCR and fear conditioning, respectively. Pharmacological MIF inhibition was achieved with intraperitoneal injections of ISO-1 (daily, IP, 20 mg/kg in 5% DMSO in 0.9% NaCl) for 4 weeks following ICV-STZ injection. The findings from ISO-1 treated mice were confirmed in MIF knockout C57BL/6. To assess the role of MIF in human AD, cerebrospinal fluid levels of MIF and hyperphosphorylated tau were measured using ELISA. Administration ICV-STZ resulted in hippocampal dependent cognitive impairment. MIF inhibition with ISO-1 significantly improved the STZ-induced impairment in contextual memory performance, indicating MIF-related inflammation as a major contributor to ICV-STZ-induced memory deficits. Furthermore, inhibition of the MIF resulted in reduced cytokine production in vitro and in vivo. In human subjects with AD at early clinical stages, cerebrospinal fluid levels of MIF were increased in comparison with age-matched controls, and correlated with biomarkers of tau hyper-phosphorylation and neuronal injury hinting at MIF levels as a potential biomarker for early-stage AD. The present study indicates the key role of MIF in controlling the chronic cytokine release in neuroinflammation related to tau hyperphosphorylation, neurodegeneration, and clinical manifestations of AD, suggesting the potential of MIF inhibition as therapeutic strategy to slow down neurodegeneration and clinical disease progression

Designing cost-sharing methods for Bayesian games

We study the design of cost-sharing protocols for two fundamental resource allocation problems, the Set Cover and the Steiner Tree Problem, under environments of incomplete information (Bayesian model). Our objective is to design protocols where the worst-case Bayesian Nash equilibria, have low cost, i.e. the Bayesian Price of Anarchy (PoA) is minimized. Although budget balance is a very natural requirement, it puts considerable restrictions on the design space, resulting in high PoA. We propose an alternative, relaxed requirement called budget balance in the equilibrium (BBiE).We show an interesting connection between algorithms for Oblivious Stochastic optimization problems and cost-sharing design with low PoA. We exploit this connection for both problems and we enforce approximate solutions of the stochastic problem, as Bayesian Nash equilibria, with the same guarantees on the PoA. More interestingly, we show how to obtain the same bounds on the PoA, by using anonymous posted prices which are desirable because they are easy to implement and, as we show, induce dominant strategies for the players

An experimental investigation on the transient heat transfer characteristics using air/water droplets two-phase flow

The present study focused on evaluating the heat transfer behavior and predicting the surface resulting status during air/water droplets two-phase flow. Transient heat transfer based on the lumped capacitance model (LCM) was investigated experimentally under a range of water droplets concentration, surface temperature, and varying Re number. Compared with a single-phase air cooling, the transient surface temperature decreased with the increase in water droplets concentration and Re number. At the same cooling time, the surface temperature decreases about 13.5%, 47%, and 53.2% for (j = 46.79 - 111.68 kg/m2 hr). It was also noticed that the heat transfer coefficient increased with the increase in water droplets concentration and reach its maximum value at (j = 111.68 kg/m2 hr). Based on the analysis of the experimental results, the heat transfer mechanism due to the impacting of water droplets on the sphere surface was classified into three important physical regimes. Clear convection heat transfer regime corresponds to the dry region (region I); Convection and evaporation regimes correspond to the dry-out and wet regions (region II and III). © 2020 Institute of Physics Publishing. All rights reserved

Experimental investigation of hydrodynamics and heat transfer of sphere cooling using air/water mist two phase flow

To improve the cooling performance for the future generation of gas-cooled equipment, experimental studies on air/water mist heat transfer of single sphere inside a cylindrical channel have been carried out with an aim to investigate the heat transfer enhancement by suspending tiny water mist into air flow. The effect of the different key factors such the inlet Reynolds number, surface heat flux and water flux density on friction flow and heat transfer characteristics are examined. Experiments were performed in five cases using air as well as air/water mist two phase flow as working coolant for range of water flux density (j = 23.39-111.68 kg m-2 hr-1). The results obtained from the related experimental work revealed that the presence of water mist leads to a significant increase in heat transfer over the use of air coolant alone. The Nusselt numbers are respectively 1%, 19.7%, 90.2% and 134% higher than those in single phase-cooling for all cases of water flux density respectively. It was also found that the water flux density has little influence on friction factor. When the surface heat flux is fixed, the heat transfer enhancement factor increases with the increasing of water flux density. © Published under licence by IOP Publishing Ltd.The work was supported by Act 211 02.A03.21.000