RESUMEN
Functional electrical stimulation (FES) neuroprostheses have been regarded as an effective approach for gait rehabilitation and assisting patients with stroke or spinal cord injuries. A multiple-channel FES system was developed to improve the assistance and restoration of lower limbs. However, most neuroprostheses need to be manually adjusted and cannot adapt to individual needs. This study aimed to integrate the purely reflexive FES controller with an iterative learning algorithm while a multiple-channel FES walking assistance system based on an adaptive reflexive control strategy has been established. A real-time gait phase detection system was developed for accurate gait phase detection and stimulation feedback. The reflexive controller generated stimulation sequences induced by the gait events. These stimulation sequences were updated for the next gait cycle through the difference between the current and previous five gait cycles. Ten healthy young adults were enrolled to validate the multiple-channel FES system by comparing participants' gait performance to those with no FES controller and purely reflexive controller. The results showed that the proposed adaptive FES controller enabled the adaption to generate fitted stimulation sequences for each participant during various treadmill walking speeds. The maximum, minimum, and range of motion (ROM) of the hip, knee, and ankle joints were furtherly improved for most participants, especially for the hip and knee flexion and ankle dorsiflexion compared with the purely reflexive FES control strategy. The presented system has the potential to enhance motor relearning and promote neural plasticity.
RESUMEN
An Al 6061/Mg AZ31B composite plate with good bonding and excellent comprehensive mechanical properties was prepared through solid-liquid cast-rolling bonding (SLCRB). The microstructure evolution and mechanical behavior of Al/Mg composite plates under different rolling passes were studied. The results showed that with the increase of rolling passes, the bonding layer of the composite plate was crushed, and the base material on both sides of the substrate gradually grew towards the broken part of the bonding layer. The microstructure on both sides of the substrate extended along the rolling direction and was dynamically recrystallized to a certain extent. In the Mg substrate, because the preheating temperature was higher than its recrystallization temperature, with the increase of rolling passes, the grains in Mg substrate were crystallized. When the rolling passes reached the fourth pass, complete recrystallization basically took place in the Mg substrate. With the change of the internal structure and bonding layer on both sides of the substrate, the mechanical properties of the composite plate can be improved gradually. The tensile strength increased from 136 MPa before rolling to 190 MPa at the fourth pass, and the shear strength increased from 74 MPa to 98 MPa, with growth rates of about 40% and 32%, respectively. The elongation of the composite plate decreased from 6.3% to 5.4%, a decrease of about 1%.
RESUMEN
In this work, a citric acid monohydrate (CAM)-templated polydimethylsiloxane (PDMS) sponge was proposed to mimic heterogeneous pore structures in the soil for plant cultivation. The porosity of the PDMS sponges was tuned by adjusting the CAM template. The water intake capability of the sponge was improved by (3-Aminopropyl) triethoxysilane (APTES) functionalization. The pore size and pore distribution were characterized by SEM and micro-computed tomography (micro-CT). The effect of pore structures on Oryzasativa (O. sativa) growth was investigated. Also, a 3D multi-layer PDMS sponge assembling was proposed to mimic the heterogeneous pore distribution at the different soil depth. The different growth rates of O. sativa and Nicotiana tabacum L. (N. tabacum) seeds on porous PDMS sponge indicated the impact of physical obstacles (pores) and chemical (water content) conditions on plant development. It is anticipated that this PDMS sponge could serve as a 3D matrix to mimic soil and provide a new idea for plant cultivation.