Reinforcement learning control for coordinated manipulation of multi-robots

In this paper, coordination control is investigated for multi-robots to manipulate an object with a common desired trajectory. Both trajectory tracking and control input minimization are considered for each individual robot manipulator, such that possible disagreement between different manipulators can be handled. Reinforcement learning is employed to cope with the problem of unknown dynamics of both robots and the manipulated object. It is rigorously proven that the proposed method guarantees the coordination control of the multi-robots system under study. The validity of the proposed method is verified through simulation studies

Normobaric hyperoxia protects the blood brain barrier through inhibiting Nox2 containing NADPH oxidase in ischemic stroke

Normobaric hyperoxia (NBO) has been shown to be neuro- and vaso-protective during ischemic stroke. However, the underlying mechanisms remain to be fully elucidated. Activation of NADPH oxidase critically contributes to ischemic brain damage via increase in ROS production. We herein tested the hypothesis that NBO protects the blood-brain barrier (BBB) via inhibiting gp91phox (or called Nox2) containing NADPH oxidase in a mouse model of middle cerebral artery occlusion (MCAO). Wild-type C57/BL6 mice and gp91phoxknockout mice were given NBO (95% O2) or normoxia (21% O2) during 90-min MCAO, followed by 22.5 hrs of reperfusion. BBB damage was quantified by measuring Evans blue extravasation. The protein levels of matrix metalloproteinase-9 (MMP-9), tight junction protein occludin and gp91phox were assessed with western blot. Gel zymography was used to assess the gelatinolytic activity of MMP-9. In the wild type mice, cerebral ischemia and reperfusion led to remarkable Evans blue extravasation, significantly increased gp91phox and MMP-9 levels and decreased occludin levels in the ischemic brain tissue. In gp91phox knockout mice, the changes in Evans blue extravasation, MMP-9 and occludin were at much smaller magnitudes when compared to the wild type. Importantly, NBO treatment significantly reduced the changes in all measured parameters in wild type mice, while did not cause additional reductions in these changes when gp91phox was knocked out. These results indicate that activation of Nox2 containing NADPH oxidase is implicated in the induction of MMP-9, loss of occludin and BBB disruption in ischemic stroke, and inhibition of Nox2 may be an important mechanism underlying NBO-afforded BBB protection

Static Human Detection and Scenario Recognition via Wearable Thermal Sensing System

Conventional wearable sensors are mainly used to detect the physiological and activity information of individuals who wear them, but fail to perceive the information of the surrounding environment. This paper presents a wearable thermal sensing system to detect and perceive the information of surrounding human subjects. The proposed system is developed based on a pyroelectric infrared sensor. Such a sensor system aims to provide surrounding information to blind people and people with weak visual capability to help them adapt to the environment and avoid collision. In order to achieve this goal, a low-cost, low-data-throughput binary sampling and analyzing scheme is proposed. We also developed a conditioning sensing circuit with a low-noise signal amplifier and programmable system on chip (PSoC) to adjust the amplification gain. Three statistical features in information space are extracted to recognize static humans and human scenarios in indoor environments. The results demonstrate that the proposed wearable thermal sensing system and binary statistical analysis method are efficient in static human detection and human scenario perception

Sex-specific competition differently regulates ecophysiological responses and phytoremediation of Populus cathayana under Pb stress

Lead (Pb) contamination seriously threatens agroforestry production and safety. We aim to determine the interactive influence of Pb and sexual competition on the growth performance, photosynthetic and biochemical traits, ultrastructure and phytoremediation-related parameters of males and females. In the present study, eco-physiological responses and phytoremediation traits of Populus cathayana females and males were evaluated under interactive treatments of Pb and competition. There were significant sex-specific competition effects on biomass partition, photosynthetic activities, carbohydrate contents, nitrogen and phosphorus use efficiencies, ultrastructure and phytoremediation under Pb stress. When competition within the same sex was compared, females were more sensitive to Pb stress, while males possessed greater Pb contents, and a higher bioconcentration factor and tolerance index. Under inter-sexual competition, males alleviated competition effects through greater Pb absorption, and lower photosynthetic rates, nutrient use efficiencies and biomass accumulation. Moreover, Pb stress altered competition intensities of both sexes. Sex-specific competition and neighbor effects may regulate responses and phytoremediation under heavy metal stress in dioecious plants. In the future, more attention should be paid on the effects of inter- and intra-sexual competition on dioecious species in the process of forestation and restoration of contaminated soil.Peer reviewe

Stackelberg game-based optimal electricity trading method for distribution networks with small-micro industrial parks

In order to improve the operating benefits of the distribution network (DN) and reduce the energy consumption costs of small-micro industrial parks (SMIPs), a two-layer optimal electricity trading method for DN with SMIPs is proposed. First, based on the Stackelberg game, a multi-objective two-layer optimal trading model for DN and SMIP is established. In the upper layer, the DN agent is regarded as the leader, and a trading model is established with the goal of maximizing the profits of agents. In the lower layer, an energy optimization model is proposed for the SMIP operators, which are regarded as the followers, with the goal of minimizing the operating costs. According to the buying and selling electricity prices at the upper and lower layers, a dynamic pricing strategy is formulated. The Karush–Kuhn–Tucker condition (KKT) is introduced to transform the two-layer model into a single-layer model, and based on linear transformations, the model is further converted into a mixed-integer linear programming model. The transformations aim to address the non-linear issues arising from multivariable coupling between the upper and lower-layer trading models. The simulation results show that the trading strategy proposed in this paper can effectively increase the profit of DNs while reducing the operating costs of SMIPs and can provide a reference for decision-making in the electricity market (EM) with the participation of SMIP

Nonlinear dynamic analysis on maglev train system with flexible guideway and double time-delay feedback control

In this paper, the dynamic behavior of time-delayed feedback control for maglev train system with double discrete time delays is considered with flexible guideway. Considering the maglev guideway as Beroulli-Euler beam, the mathematical model of maglev system with flexible guideway is constructed. The time delay of the two state feedback signals in the maglev system occurs simultaneously, and the values are different. The present treatment method only considers one single feedback delay, which are insufficiency. Thus, the Hopf bifurcation with double time-delay feedback of maglev train running on the flexible guideway is analyzed considering time-delayed position feedback signal τ1 and velocity feedback signal τ2. A novel method is presented to develop the double-parametric Hopf bifurcation diagram in relation to τ1 and τ2. Sufficient numerical simulations are provided to illustrate the complex dynamical behavior of the discrete delays τ1 and τ2 for maglev system and we verify the obtained theoretical analysis. Finally, the field experiments are carried out to validate the effectiveness of the Hopf bifurcation analytical method preliminarily

Advances in stem cell therapy for sensory nerve injury

Sensory nerves belong to the afferent nerve part of the peripheral nervous system. Their role is to accept the stimuli inside and outside the body and transmit them to the center nerve system to form sensations or reflexes. Sensory nerve damage can be caused by trauma, tumor invasion, surgical injury, etc. Sensory nerve injury may cause decline or loss of some sensory organs function in patients. Damage of important sensory nerves such as optic nerves and auditory nerves can bring profound troubles to patients' lives. So far, the main clinical method to repair sensory nerves is autologous nerve transplantation. However, its application is limited by various factors, and the recovery effect of nerve function is often limited. Stem cells have the potential of multi-directional differentiation, which can differentiate into Schwann cells, and then secrete neurotrophic factors to promote axonal growth and myelin regeneration. Schwann cells directionally proliferate and form Büngner zones which guide nerve regeneration. Stem cells can also differentiate into neurons and construct nerve defect repair materials, which is an ideal choice for nerve repair. At present, the tissue engineering technology based on stem cells, combined with several key biotechnology, such as the use of biopolymerized or artificial surface micro-patterning nerve conduit to bridge nerve defects, and the use of microspheres to achieve the controlled release of extracellular matrix proteins and neurotrophic factors, is being widely studied and has achieved certain research results. This article reviews the research progress of stem cells in the repair of several major sensory nerves, such as optic nerves, olfactory nerves, cochlear nerves and sensory nerve fibers of sciatic nerve, expecting to provide a new perspective for neural repair of stem cells, broaden the preclinical research in nerve repair, and provide reference for follow-up clinical application

Effects of step lengths on biomechanical characteristics of lower extremity during split squat movement

Objective: To quantify the effects of increasing the step length of the split squat on changes in kinematics, kinetics, and muscle activation of the lower extremity.Methods: Twenty male college students participated in the test (age: 23.9 ± 3.7, height: 175.1 ± 4.9). Data on kinematics, kinetics, and EMG were collected during split squat exercise at four different step lengths in a non-systematic manner. One-way repeated measurements ANOVA were used to compare characteristic variables of peak angle, moment, and RMS among the four step length conditions.Results: The step length significantly changes the peak angles of the hip (p = 0.011), knee (p = 0.001), ankle (p < 0.001) joint, and the peak extension moment of the hip (p < 0.001), knee (p = 0.002) joint, but does not affect the ankle peak extension moment (p = 0.357) during a split squat. Moreover, a significant difference was observed in the EMG of gluteus maximus (p < 0.001), vastus medialis (p = 0.013), vastus lateralis (p = 0.020), biceps femoris (p = 0.003), Semitendinosus (p < 0.001), medialis gastrocnemius (p = 0.035) and lateralis gastrocnemius (p = 0.005) during four step lengths, but no difference in rectus femoris (p = 0.16).Conclusion: Increases in step length of split squat had a greater activation on the hip extensor muscles while having a limited impact on the knee extensor muscles. The ROM, joint moment, and muscle activation of the lead limb in the split squat all should be considered in cases of individual preventative or rehabilitative prescription of the exercise. Moreover, the optimal step length for strength training in healthy adults appears to be more suitable when it is equal to the length of the individual lower extremity