Reconfigurable Disk-like Microswarm under a Sawtooth Magnetic Field

Swarming robotic systems, which stem from insect swarms in nature, exhibit a high level of environmental adaptability and enhanced tasking capabilities for targeted delivery and micromanipulation. Here, we present a strategy that reconfigures paramagnetic nanoparticles into microswarms energized by a sawtooth magnetic field. A rotary-stepping magnetic-chain mechanism is proposed to address the forming principle of disk-like swarms. Based on programming the sawtooth field, the microswarm can perform reversible transformations between a disk, an ellipse and a ribbon, as well as splitting and merging. In addition, the swarms can be steered in any direction with excellent maneuverability and a high level of pattern stability. Under accurate manipulation of a magnetic microswarm, multiple microparts with complicated shapes were successfully combined into a complete assembly. This reconfigurable swarming microrobot may shed light on the understanding of complex morphological transformations in living systems and provide future practical applications of microfabrication and micromanipulation.

Spin Dependent Transport through Driven Magnetic System with Aubry-Andre-Harper Modulation

In this work, we put forward a prescription of achieving spin selective electron transfer by means of light irradiation through a tight-binding (TB) magnetic chain whose site energies are modulated in the form of well known Aubry–Andre–Harper (AAH) model. The interaction of itinerant electrons with local magnetic moments in the magnetic system provides a misalignment between up and down spin channels which leads to a finite spin polarization (SP) upon locating the Fermi energy in a suitable energy zone. Both the energy channels are significantly affected by the irradiation which is directly reflected in degree of spin polarization as well as in its phase. We include the irradiation effect through Floquet ansatz and compute spin polarization coefficient by evaluating transmission probabilities using Green’s function prescription. Our analysis can be utilized to investigate spin dependent transport phenomena in any driven magnetic system with quasiperiodic modulations.

On the energy efficiency of electromechanical systems with an electromagnetic vibration exciter

Study shake the phenomena in the electromechanical systems (EMS) are presented by permanent interest for the wide circle of researchers. The most effective source of vibrations in many cases is an electromagnetic causative vibration exciters (EMCV) in that there is transformation of electric power to energy of mechanical vibrations, that is related to the change of inductance. Electromagnetic vibration exciters have a number of significant advantages over other types of exciters. Due to the absence of rubbing parts they have high reliability and durability. They allow you to smoothly adjust the amplitude of vibrations over a wide range. EMCV are easy to integrate into production lines, they have easy maintenance, low operating costs and extensive automation capabilities. This phenomenon presents interest at development of electromechanics devices for intensive vibrotechnologies. Especially development guided on frequency of resonant EMCV promotes the economy of consumption of electric power and productivity of vibrotechnique. To the article the results of theoretical and experimental researches are driven on the increase of energy efficiency of EMCV and determination of output-input ratio. It is shown that losses of electric power in EMS with EMCV related to the origin of permanent constituents and ultra-harmonics of current, choice of magnetic chain and dynamic.