Secondary Structure and X-ray Crystallographic Analysis of the Glideosome-Associated Connector (GAC) from Toxoplasma gondii

A model for parasitic motility has been proposed in which parasite filamentous actin (F-actin) is attached to surface adhesins by a large component of the glideosome, known as the glideosome-associated connector protein (GAC). This large 286 kDa protein interacts at the cytoplasmic face of the plasma membrane with the phosphatidic acid-enriched inner leaflet and cytosolic tails of surface adhesins to connect them to the parasite actomyosin system. GAC is observed initially to the conoid at the apical pole and re-localised with the glideosome to the basal pole in gliding parasite. GAC presumably functions in force transmission to surface adhesins in the plasma membrane and not in force generation. Proper connection between F-actin and the adhesins is as important for motility and invasion as motor operation itself. This notion highlights the need for new structural information on GAC interactions, which has eluded the field since its discovery. We have obtained crystals that diffracted to 2.6–2.9 Å for full-length GAC from Toxoplasma gondii in native and selenomethionine-labelled forms. These crystals belong to space group P212121; cell dimensions are roughly a = 119 Å, b = 123 Å, c = 221 Å, α = 90°, β = 90° and γ = 90° with 1 molecule per asymmetric unit, suggesting a more compact conformation than previously proposed

Secondary Structure and X-Ray Crystallographic Analysis of the Glideosome-Associated Connector (GAC) from Toxoplasma gondii

A model for parasitic motility has been proposed in which parasite filamentous actin (F-actin) is attached to surface adhesins by a large component of the glideosome, known as the glideosome-associated connector protein (GAC). This large 286 kDa protein interacts at the cytoplasmic face of the plasma membrane with the phosphatidic acid-enriched inner leaflet and cytosolic tails of surface adhesins to connect them to the parasite actomyosin system. GAC is observed initially to the conoid at the apical pole and re-localised with the glideosome to the basal pole in gliding parasite. GAC presumably functions in force transmission to surface adhesins in the plasma membrane and not in force generation. Proper connection between F-actin and the adhesins is as important for motility and invasion as motor operation itself. This notion highlights the need for new structural information on GAC interactions, which has eluded the field since its discovery. We have obtained crystals that diffracted to 2.6-2.9 Å for full-length GAC from Toxoplasma gondii in native and selenomethionine-labelled forms. These crystals belong to space group P212121, cell dimensions are roughly a=119 Å, b=123Å, c=221Å, α=90, β=90, γ=90 with 1 molecule per asymmetric unit, suggesting a more compact conformation than previously proposed.

A Comparative Study of Nonlinear Control Schemes for Induction Motor Operation Improvement

In the objective of improving the performance of induction motor operation and ensuring a robust control against different uncertainties and external disturbances, especially at low-speed regions, this research highlights the main features of two nonlinear control techniques. First, the control design is based on the backstepping approach (BSA) with integral action, and then the sliding mode control (SMC) theory. The BSA principle is to define successive causal relations in order to construct the control law in a recursive and systematic way. This allows overcoming the obstacle of the higher-order system's dimension. SMC is designed to drive and then constrain the system state to lie within a neighborhood of the switching surface, this provides very strong and inherent robustness to the resulting controllers. The main reason behind developing the nonlinear control techniques is to ensure a decoupled control of the machine. Besides, it guarantees the stability of the overall system by tracking the speed reference with the fewest static error. Moreover, as the sensorless control increases the reliability and decreases the cost of the control system, an extended Kalman filter is implemented to improve speed and flux observation. The simulations of all the discussed results have been obtained by MATLAB/Simulink.

Lubricating oils impact crankshaft rotation speed in outboard motors

The most effective assessment of the quality of transmission and motor lubricating oils for marine engines in general and of outboard motors in particular can be given by practical tests on real engines. An important factor for improving the technical characteristics of outboard motors by reducing friction in the movable joints of the internal combustion engine and gearbox is the right choice of a lubricating oil. The stability of the engine crankshaft rotating speed, reducing noise and vibration during the outboard motor operation indicate good lubricating properties of the engine and transmission oil used. There are shown the results of comparative tests of outboard motors SEA-PRO T2.5 (two-stroke) and YAMAHA F4B (four-stroke) using the most common on the market lubricating oil and the oil produced by KUPPER, LLC (Russia). There are presented the illustrations of outboard motors SEA-PRO T2.5 and YAMAHA F4B. The tests were carried out in the laboratory conditions in a small experimental pool by specialists from the Outboard Motors Research and Production Laboratory of Astrakhan State Technical University. The control and measuring devices used were: a tachometer SEA-PRO TSP-02, a gas analyzer “Infrakar-A-02” with a built-in tachometer. It has been inferred that there is a direct dependence of the crankshaft rotation speed during long-term operation of the outboard motor on the quality and characteristics of the lubricating oil. The probability of the research on stationary propulsion systems in water transport is indicated.

Identification of the Technical Condition of Induction Motor Groups by the Total Energy Flow

The paper discusses the method of identifying the technical condition of induction motors by classifying the energy data coming from the main common power bus. The work shows the simulation results of induction motor operation. The correlation between occurring defects and current diagrams is presented. The developed simulation model is demonstrated. The general algorithm for conducting experiments is described. Five different experiments to develop an algorithm for the classification are conducted: determination of the motors number in operation with different power; determination of the motors number in operation with equal power; determination of the mode and load of induction electric motor; determination of the fault and its magnitude with regard to operation and load of induction motor; determination of the fault and its magnitude with regard to operation and load of induction motor with regard to non-linear load in the flow. The article also presents an algorithm for preprocessing data to solve the classification problem. In addition, the classification results are shown and recommendations for testing and using the classification algorithm on a real object are made.

Influence of Microstepping Signal Shape on Shaft Movement Precision and Torque Variation of the Stepper Motor

Stepper motors are widely used in many applications where discrete, precise movement is required. There is a variety of dedicated stepper motor controllers (sometimes referred to as “step sticks”) available on the market. Those controllers provide a number of different motor control schemes that vary by aspects like current control method, reference current shape or maximum resolution increase (microstepping). The two most widely acknowledged signal shapes are sine-cosine microstepping and quadrature microstepping. The choice of the control scheme impacts torque output, torque variation, positioning error and maximum power supply requirements. This paper presents a family of generalised microstepping signal shapes, ranging from sine-cosine microstepping to quadrature microstepping. Derivation of signal shapes as well as their mathematical analyses are provided. Those signals are then implemented on the control board. A series of experiments is performed on a test bench to analyse the influence of different signal shapes on the performance of the motor in both load and no load conditions. The comparison of the new generalized shapes influence on the motor operation to the commonly used sine-cosine and quadrature control is provided.

Investigation of the Torque Production Mechanism of Dual-Stator Axial-Field Flux-Switching Permanent Magnet Motors

This paper studies the torque production mechanism of the dual-stator axial-field flux-switching permanent magnet (DSAFFSPM) machine. Due to the double-sided slotting design of such topology, more resultant air-gap working harmonics in the air-gap flux density are responsible for the torque production and the stator air-gap permeance is especially considered in the investigation. Based on the magnetic force (MMF)-permeance model, the composition and difference of the air-gap working harmonics are demonstrated. The DSAFFSPM machine torque contributions of the main working harmonics are analyzed theoretically and quantified by finite element analysis (FEA). The influence laws of the parameters on the working harmonics are shown and this effectively improves the motor operation performance. Finally, some experiments on the DSAFFSPM machine are carried out to validate the analytical and FEA results.

High energy-efficient electrical drive with multilevel inverter and widebandgap power semiconductors

Multilevel inverters are an alternative for electrical drives with DC link voltage between 560 and 750 V. In this voltage range new wide-bandgap power switches (SiC MOSFET, GaN FET) are available. The paper analyses three-, four-, five- and seven-level inverters. A simulation model of the drive system, including the 11 kW induction motor and motor filter is developed. By replacing IGBTs with SiC FETs, the twolevel inverter achieved a loss reduction of 59 % at 25 °C and 150 °C at nominal motor operation point. By using the five-level inverter with GaN FETs, a further loss reduction of 9 % only at low junction temperature is possible. With a higher number of inverter levels, the size of the motor filter can be reduced. With five inverter levels and 40 kHz switching frequency volume and weight can be reduced by 86 % and 78 % respectively. The overall efficiency of the drive system achieves 98.5 % at 25 °C and 98.1 % at 150 °C. Compared to the state of the art (two-level with IGBTs with 5 kHz), this is an improvement of 2.1 % at 25 °C and 2.7 % at 150 °C.

Improving a model of the induction traction motor operation involving non-symmetric stator windings

The analysis of operating conditions of induction traction motors as part of traction electric drives of electric locomotives reported here has revealed that they are powered by autonomous voltage inverters with asymmetric non-sinusoidal voltage. It was established that the induction motor operation may be accompanied by defects caused by the asymmetrical modes of the motor stator. A model of the induction motor has been proposed that takes into consideration changes in the values of mutual inductance of phases and complete inductance of the magnetization circuit due to changes in the geometric dimensions of the winding caused by a certain defect. An algorithm that considers the saturation of the magnetic circuit of the electric motor has been proposed. This approach to modeling an induction motor is important because if one of the stator's windings is damaged, its geometry changes. This leads to a change in the mutual inductance of phases and the complete inductance of the magnetization circuit. Existing approaches to modeling an induction motor do not make it possible to fully take into consideration these changes. The result of modeling is the determined starting characteristics for an intact and damaged engine. The comparison of modeling results for an intact engine with specifications has shown that the error in determining the controlled parameters did not exceed 5 %. The modeling results for the damaged engine demonstrated that the nature of change in the controlled parameters did not contradict the results reported by other authors. The discrepancy in determining the degree of change in the controlled parameters did not exceed 10 %. That indicates a high reliability of the modeling results. The proposed model of an induction electric motor could be used to investigate electromagnetic processes occurring in an electric motor during its operation as part of the traction drive of electric locomotives

ATOM SEARCH OPTIMIZATION – NEURAL NETWORK FOR DRIVING DC MOTOR

DC motor applications are very widely used because DC motors are very suitable for applications, especially control. Thus, a proper DC motor controller design is required. DC motor speed control is very important to maintain the stability of motor operation. A recent type of metaheuristic algorithm that mimics the motion of atoms is introduced. Atom search optimization (ASO) is a mathematical model and duplicates the behavior of atoms in nature. Atoms intercommunicate with each other via the delivering contact force in the form of the Lennard-Jones potential and the constraint force produced from the potential bond length. The algorithm is simple and easy to be applied. In this study, the atomic search optimization (ASO) algorithm is proposed as a speed controller for the control dc motor. First, the ASO proposed by the algorithm is applied for the optimization of the neural network. Second, the ASO-NN proposal was the result compared to other algorithms. This paper compares the performance of two different control techniques applied to DC motors, namely the ASO-NN and proportional integral derivative (PID) methods. The results show that the proposed method has effectiveness. The calculation of the proposed ASO-NN control shows the best performance in the settling time. The ASO-NN method has the capability of settling time 0.04 seconds faster than the PID method.