Passive fluid control has mostly been used for valves, pumps, and mixers in microfluidic systems. The basic principle is to generate localized losses in special channel structures, such as branches, grooves, or spirals. The flow field in two-dimensional space can be easily calculated using the typical Stokes formula, but it is challenging in three-dimensional space. Moreover, the flow field with periodic variable cross-sections channeled of polyhedral units has been neglected in this research field due to previous limitations in manufacturing technology. With the continuous progress of 3D printing technology, the field of microfluidic devices ushered in a new era of manufacturing three-dimensional irregular channels. In this study, we present finite analysis results for a periodic nodular-like channel. The experiments involve variations in the Reynold number (Re), periodic frequency, and comparative analyses with conventional structures. The findings indicate that this variable 3D cross-section structure can readily achieve performance comparable to other passive fluid control methods in valve applications. A 3D model of the periodic tetrahedron channel was fabricated using 3D printing to validate these conclusions. This research has the potential to significantly enhance the performance of passive fluid control units that have long been constrained by manufacturing dimensions.

Background: The slewing crane is easily affected by the wind and the manipulation level of the operator when it is working, which in turn impacts its swing angle, affects the working efficiency and safety of the crane. Objective: Toimprove the operation safety andreduce the swing angle, this study design and research the anti-swing control system for the slewing crane. Methods: Firstly, based on the Lagrange equation, the dynamic model of the crane hoisting system is established. Then, the mechanical anti-swing mechanism driven by a four-motor rope is established. Finally, based on fuzzy PID control, an anti-swing platform is established, and the performance of anti-swing control is verified. Results: Compared to no anti-swing control, the in-plane swing angle θ₁ and out-of-plane swing angle θ₂ of the lifting arm are reduced by 88% and 75% respectively. Conclusion: The results show that the four-motor rope-driven anti-swing mechanism can achieve better anti-swing effect, which provides an effective swing suppression method for the slewing crane in the actual operation.

More hemiplegia patients tend to use equipment for rehabilitation training due to the lack of physical therapists and the low effect of manual training. Nowadays, lower limb rehabilitation training devices for patients in grade 2 of the Medical Research Council (MRC-2) scale are still scarce and have some issues of poor autonomy and cannot relieve the muscle weakness of patients. To address these problems, a prototype based on gravity balance was designed with the combination of springs and linkages to enable patients to passively experience the rehabilitation training in the state of balancing the gravity of lower limbs. The motion of the mechanism was analyzed to obtain the functional relation between the motor rotation angle and the joints’ angle. Based on the principle of constant potential energy, a gravity balance mathematical model of the device was established, analyzed, and simulated. Moreover, through the training experiment, the results show that when subjects in three different weights were trained under the rehabilitation device with and without gravity balance, the required torques of the motor and EMG signal strength of the knee and hip joints decreased by a degree of significance, which verified the effectiveness of the device’s gravity balancing characteristics for MRC-2 patients.

The SC200 cyclotron is the critical component of the proton therapy system, which is being jointly developed by the Institute of Plasma Physics Chinese Academy of Sciences (ASIPP), Hefei, China, and the Joint Institute for Nuclear Research (JINR), Dubna, Russia. It is an isochronous cyclotron to accelerate H ⁺ ions and extract proton beam energies of 75-200 MeV with the maximum beam intensity of 1 μA. The maximum magnetic field intensity of the SC200 cyclotron is 4.6 T, and the accuracy of measurements for the average isochronous field is required to be better than 10 ^-4 . The magnetic gap decreases from 37 mm at cyclotron center to 9 mm at the pole edge. Hence, the difficulty of designing a magnetic field measurement system is increased because of the required magnetic field accuracy and the narrow gap between the poles. A measurement system has been developed to measure the magnetic field distribution in the median plane of the cyclotron by the SENIS Hall probe. After the Hall probe is calibrated by NMR, the measurement accuracy can reach ±4 × 10 ^-4 under the magnetic field intensity of 5 T. The position of the Hall probe will be monitored by grating and optical encoder, respectively, so as to ensure its correct positions. To verify the performance of the mapping system, it has been tested in the SC200 cyclotron with the designed vacuum degree. The test results showed that the mapping system can run smoothly and meet the measurement requirements of the SC200 cyclotron.

The superconducting cyclotron for proton therapy that is under design by ASIPP (Hefei, China) and JINR (Dubna, Russia) will be able to accelerate protons to the energy 200 MeV with the maximum beam current of 1 μA. The performance of superconducting magnets is the key to the superconducting cyclotron, and it will directly affect the quality of the proton beam and the therapeutic effect. To measure the magnetic induction intensity of the superconducting coil with the cryogenic Hall probes on the testing platform. As the current has been increased from 0 to 160 A, the measurement error of probes decreases obviously whose tendencies are consistent. By comparing the measuring results with the theoretical results, we can confirm the quality of superconducting coil and the installation location. Meanwhile, the basic operation of cryogenic Hall probes and data acquisition system is grasped, and the experimental experience for the magnetic intensity test of superconducting cyclotron has been accumulated.

This paper proposes a kinesthetic–tactile fusion feedback system based on virtual interaction. Combining the results of human fingertip deformation characteristics analysis and an upper limb motion mechanism, a fingertip tactile feedback device and an arm kinesthetic feedback device are designed and analyzed for blind instructors. In order to verify the effectiveness of the method, virtual touch experiments are established through the mapping relationship between the master–slave and virtual end. The results showed that the average recognition rate of virtual objects is 79.58%, and the recognition speed is improved by 41.9% compared with the one without force feedback, indicating that the kinesthetic–tactile feedback device can provide more haptic perception information in virtual feedback and improve the recognition rate of haptic perception.