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• A new non-resonant and free/impact motion based EMEH with steel frame for ultra-low frequency and large amplitude vibration application is proposed. • Mathematical model and simulation procedure are established and well validated. • Experimental results are analyzed and show the valuable features of the proposed EMEH. In this paper, a new non-resonant, free motion based electromagnetic energy harvester is proposed for harvesting energy from low-frequency vibration sources. In this design, steel frame is beneficially utilized to enhance the flux and consequently the power density of the harvester. The steel frame can also function as a magnetic shield to protect the harvester from external magnetic field interferences. Prototype of this harvester is constructed and characterized experimentally. A dedicated model and simulation method including non-linear contact characteristics is presented in this paper for predicting the dynamic response of this harvester at different vibration frequencies and amplitudes, and different operation modes are characterized. The measured results have well validated the behaviors predicted by the proposed model. In particular, the developed prototype of this harvester can generate a power density 748 μW/c m 3 at a low-frequency of 4.5 Hz and 40 mm vibration amplitude. Compared to recently reported low-frequency energy harvesters summarized in Table 3 , this new harvester has the superiority of high-power density. It is a non-resonant harvester so it can harvest energy for a wide frequency band. [ABSTRACT FROM AUTHOR]

Atrazine is considered as a potential environmental endocrine disruptors and exhibits various toxic effects on animals. It has a great impact in the aquatic ecosystems, but there are few studies on its immunotoxicity in crustaceans. In the present study, the Procambarus clarkii were utilized to assess the immune toxicity after 0.5 mg/L and 5 mg/L atrazine exposure. A significant decrease in total hemocytes count (THC) was observed at 5 mg/L atrazine exposure throughout the experiment. The activities of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were significantly inhibited, but the content of reactive oxygen species (ROS) and malondialdehyde (MDA) were up-regulated, indicating the potential oxidative stress. The analysis of the integrated biomarker response (IBR) showed the induction of oxidative stress biomarkers and the inhibition of antioxidants. After 5 mg/L atrazine exposure for 144 h, the integrity of crayfish hepatopancreas was destroyed with disappeared connections between tubules and increased liver tubules vacuoles. The relative expression levels of different immune genes in hepatopancreas after atrazine exposure were measured. Most of these genes were suppressed and exhibited a certain dose-dependent effect. The results of crayfish white spot syndrome virus (WSSV) replication shown the amount of virus in muscle was significantly higher and exhibited a higher mortality rate at 5 mg/L group than other groups. The present study determined the impact of atrazine exposure on WSSV outbreaks, and also provide an important basis for further assessing the occurrence of pesticides on diseases of P. clarkii. • Atrazine exposure could decrease the amount of hemocyte of P. clarkii. • Atrazine exposure inhibit the activities of antioxidant and immune-related enzymes. • Atrazine exposure (5 mg/L, 144 h) could destroy the integrity of hepatopancreas. • The expression of immune effectors were mostly inhibited after atrazine exposure. • Atrazine exposure enhances the proliferation of WSSV in P. clarkii. [ABSTRACT FROM AUTHOR]

• A smith predictor-based delay compensation scheme is proposed for the suppression of the undesired speed overshoot/variation phenomena caused by the speed filter. • The effectiveness and stability of the proposed solution are verified analytically and experimentally. • The robustness of the proposed solution against system parameter mismatch is verified analytically and experimentally. • The proposed structure is simple to implement with a low calculation burden and no parameters need to be tuned. The load disturbance rejection ability of the electrical machine systems is an important consideration factor in many applications, including both power generation (e.g., wind power generator) and consumption (e.g., servo systems such as high-precision machining and continuous motion in manufacturing automation). Existing studies on load disturbance rejection mainly focus on developing disturbance observers with improved steady state and dynamic performance. However, the performance of the disturbance rejection control is not only determined by the performance of the disturbance observers but also influenced by the speed response control during the transient. The latter problem might require more attention, especially due to the fact that speed filter is widely used in many actual systems to suppress the speed ripples or noise. The speed control performance would suffer from the delay caused by the filter and result in an undesired oscillatory speed response. In this paper, load disturbance rejection control based on a sliding mode disturbance observer is considered as an investigation platform, where an adaptive filter is proposed to further improve the performance of the observer. More importantly, a Smith predictor-based speed filter delay compensator is proposed to mitigate the undesired variation in the speed response caused by speed filter, achieving enhanced transient speed response under load disturbance. This structure is simple to implement, and no control parameters need to be tuned. The effectiveness of the proposed solution has been verified on a permanent magnet synchronous machine drive system. [ABSTRACT FROM AUTHOR]

• Design a frequency-adaptive and parameters-robustness PIR controller for PMSM system. • Making a tradeoff between stability margin and harmonic suppression capability. • Ensuring the stability of the original system not being affected by PIR controller. • Improving the steady-state precision without affecting the transient performance. An adaptive proportional-integral-resonant (PIR) controller with piecewise phase compensation is proposed to suppress the steady-state speed ripple of permanent magnet synchronous motor (PMSM) drive due to current measurement error. The frequency-varying characteristic of PMSM drive makes the parameters determination of the resonant controller more complicated when considering frequency adaptation. In this paper, after theoretical analysis on the current measurement error, the resonant controller is added in the speed PI loop of the PMSM vector control system, which makes the system more prone to instability. In order to ensure the stability of the system at different speeds, the resonant gain is firstly restricted by root locus method to get a stable system in the full speed range. Then, the resonant gain and the phase angel are further designed to obtain a robust vector margin by Nyquist diagram in different speed ranges. Such piecewise phase compensation method can achieve good stability margin and harmonic suppression ability by making a trade-off between them, avoiding the complicated calculation of the trigonometric functions for compensation in real time. Both steady and transient experiment results indicate that the proposed PIR controller can well restrain the frequency-varying speed ripples caused by current measurement error. [ABSTRACT FROM AUTHOR]

Most of the existing (BLDCM) brushless dc motor drive systems are designed with the traditional drive scheme for long-time operation. For short-time and heavy-duty applications, there are problems of energy consumption, large volume, heavyweight and high-cost. In this paper, a new short-time high-overload BLDCM drive system based on "electronic flywheel" and time-division switching control is proposed, which includes three core contents: a crushing chamber based on combined cutter head, an energy storage device based on an "electronic flywheel" and high overload factor BLDC using a new calculation method of capacitance and a speed control system based on time-division switching control of the speed loop and the current loop. To prove the effectiveness of the proposed scheme, a kitchen garbage processor is developed and tested. The results show that the "electronic flywheel" energy storage driving device designed in this paper is able to provide most of the energy required in the heavy-duty driving process. The designed time-division switching control scheme can well meet the control requirements for the short-time heavy load drive of the kitchen waste processor. Compared with the traditional long-time rated load drive scheme, the proposed system has the advantages of energy-saving, small volume, lightweight and low-cost. [ABSTRACT FROM AUTHOR]

The high-response and self-adaptive yarn delivery system used in weft accumulator is a critical component for improving the efficiency and quality of textile machinery. However, the existing drive system in the weft accumulator has problems such as slow start-up and slow speed-tracking responses, giving difficulties in achieving a high-efficient yarn delivery of the textile machinery. In this paper, a high-response self-balancing sensorless integrated control system of the induction motor for weft accumulator is proposed. Firstly, to enable the motor to start and respond adaptively and quickly to the number of yarn control loops and the speed control of the external equipment, a high-response sensorless vector control system for induction motor based on improved model reference adaptive control(MRAC) is proposed. Secondly, to achieve a high-response adaptive tracking performance of yarn input and output numbers and spool shaft speed, a self-balancing control strategy based on optical electromechanically integrated closed-loop control is proposed. For proving the effectiveness of the proposed scheme, a corresponding test platform was constructed for testing and validation. It can be observed from the results that the system designed in this paper has fast starting speed and better speed tracking performance, satisfying yarn delivery requirements at different speeds with high-response and adaptability. [ABSTRACT FROM AUTHOR]