Optimal Design of Magnetic Torque for a Hydraulic-Magnetic Rotary Hole Cleaning Tool in Horizontal Drilling

Summary The cleanliness of wellbore is a key factor in the drilling speed and quality of an oil field, especially in long horizontal sections of horizontal wells. Therefore, a hydraulic-magnetic rotary hole cleaning tool has been designed that does not rely on the rotary action of the drillpipe and could be used with a downhole motor to improve hole cleaning efficiency. However, the influence of magnet shape on the transmission of magnetic torque has remained unclear, such that the magnetic shaft transmission torque needed to be optimized to ensure efficient tool operation. In this study, magnetic field control equations were established in the region of the permanent magnet and air gap, and the magnetic flux distribution and magnetic torque generated between two magnetic axes in each field were calculated. Also, the influence of various magnetic field parameters on magnetic torque conduction of a strip magnet were compared and analyzed and then confirmed by comparison with experimental results. The results showed that the magnetic torque transmitted by strip magnets varied sinusoidally with magnetic axis deviation angles and that the highest torque was generated in the 12-pole model. However, the rate of increase in magnetic torque with magnet thickness was opposite to that of tile magnets, increasing with increasing magnet thickness. Magnetic torque variation with covered area was specific in the 6-pole model, showing a tendency of increasing and then decreasing. When magnet thickness was 12 mm and magnet coverage area in the effective cross section of the tool was 80%, the highest magnetic torque/unit volume of magnet was generated for achieving economic optimization. The results led to conclusions that, by solving the regional magnetic field, the magnetic torque change characteristics during movement of the magnetic drive mechanism of the hydraulic-magnetic rotary hole cleaning tool were simulated successfully and that these results could be used as an optimization analysis method for the magnetic drive mechanism of such tools.

The Flow-Heat Coupling Study of Cooling Circulating Channel of Magnetic Drive Pump

The medium in the cooling circulation channel of the magnetic drive centrifugal pump will take away the heat generated by the magnetic eddy current and bearing friction in time to avoid the high temperature demagnetization phenomenon of the permanent magnets. Therefore, the reasonable design of the cooling circulation channel directly affects the stable operation of the magnetic drive centrifugal pump. In this paper, the heat exchange and temperature distribution in the cooling circulating channel of magnetic drive pump are studied by means of numerical calculation of fluid-heat coupling and external characteristic test. The temperature distribution and development law of the isolation sleeve clearance, the bottom of the isolation sleeve and the reflow hole are analysed emphatically, and the convection heat transfer coefficient distribution in the isolation sleeve clearance is studied.

Recent progress in magnetic applications for micro- and nanorobots

In recent years, magnetic micro- and nanorobots have been developed and extensively used in many fields. Actuated by magnetic fields, micro- and nanorobots can achieve controllable motion, targeted transportation of cargo, and energy transmission. The proper use of magnetic fields is essential for the further research and development of micro- and nanorobotics. In this article, recent progress in magnetic applications in the field of micro- and nanorobots is reviewed. First, the achievements of manufacturing micro- and nanorobots by incorporating different magnetic nanoparticles, such as diamagnetic, paramagnetic, and ferromagnetic materials, are discussed in detail, highlighting the importance of a rational use of magnetic materials. Then the innovative breakthroughs of using different magnetoelectric devices and magnetic drive structures to improve the micro- and nanorobots are reviewed. Finally, based on the biofriendliness and the precise and stable performance of magnetic micro- and nanorobots in microbial environments, some future challenges are outlined, and the prospects of magnetic applications for micro- and nanorobots are presented.

Optimal Design of a Novel Magnetic Twisting Device Based on NSGA-II Algorithm

This paper presents a novel magnetic twisting device with a coaxial double rotor based on non-contact transmission characteristics of magnetic drive technology. When the twisting device rotates one cycle, the yarn can get triple twists. This means the new device can twist three times more than what the traditional single twist does. The structure of the magnetic twisting device is designed according to the twisting principle. The influence of main structural parameters on the magnetic torque is analyzed. To optimize the maximum transmission torque and the minimum magnet volume, the multi-objective optimization design model for the twisting device is established. Main parameters such as the relative angle of active disc assembly and passive disc assembly, the thickness of magnet, and the average radius of the magnet distribution are optimized by NSGA-II algorithm. Optimization results show that the proposed structural optimization design of a twisting device based on the magnetic drive has excellent performance and is effective for industrial application.

Implantation and Retrieval of Magnetic Nanobots for Treatment of Endodontic Re-Infection in Human Dentine

<div> <div> <div> <p>More than 10% of root canal treatments undergo failure worldwide due to remnant bacteria deep in the dentinal tubules located within the dentine tissue of human teeth. Owing to the complex and narrow geometry of the tubules, current techniques relying on passive diffusion of anti-bacterial agents are inadequate. Here, we present a new treatment method using actively maneuvered nanobots, which can be incorporated during standard root canal procedure. Our technique will enable dentists to execute procedures inside the dentine not yet possible by current state of the art. We demonstrate that magnetically driven nanobots can reach the depths of the tubules up to hundred times faster than current clinical practices. Subtle modifications of the magnetic drive allowed deep implantation of the nanobots isotopically distributed throughout the dentine, along with spatially controlled retrieval from selected areas. Finally, we demonstrate the integration of bactericidal therapeutic modality with the nanobots, thereby validating the tremendous potential of nanobots in dentistry, and nanomedicine in general. </p> </div> </div> </div>

Implantation and Retrieval of Magnetic Nanobots for Treatment of Endodontic Re-Infection in Human Dentine

<div> <div> <div> <p>More than 10% of root canal treatments undergo failure worldwide due to remnant bacteria deep in the dentinal tubules located within the dentine tissue of human teeth. Owing to the complex and narrow geometry of the tubules, current techniques relying on passive diffusion of anti-bacterial agents are inadequate. Here, we present a new treatment method using actively maneuvered nanobots, which can be incorporated during standard root canal procedure. Our technique will enable dentists to execute procedures inside the dentine not yet possible by current state of the art. We demonstrate that magnetically driven nanobots can reach the depths of the tubules up to hundred times faster than current clinical practices. Subtle modifications of the magnetic drive allowed deep implantation of the nanobots isotopically distributed throughout the dentine, along with spatially controlled retrieval from selected areas. Finally, we demonstrate the integration of bactericidal therapeutic modality with the nanobots, thereby validating the tremendous potential of nanobots in dentistry, and nanomedicine in general. </p> </div> </div> </div>

Anomalous Behavior of Highly Active Helical Swimmers

Artificially designed self-propelled objects can allow studying active matter phenomena with great detail that is not possible in natural, e.g. biological systems. Here, we show experimental results on helical shaped, magnetically actuated, reciprocal swimmers, where the degree of randomness in the reciprocal sequence plays an important role in determining their effective motility. Here, for the first time we show the results at high activity levels where the degree of randomness is further affected by the presence of the surface, which in turn results in a non-monotonic increase of motility as a function of magnetic drive. It will be interesting to extend these studies to denser systems where the swimmers can interact with each other through hydrodynamic forces.