Online Gait Generation Method Based on Neural Network for Humanoid Robot Fast Walking on Uneven Terrain

Haoran Zhong,Sicheng Xie,Xinyu Li,Shengyu Lu,Liang Gao 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.3

Advanced humanoid robots highlight the ability of fast walking and adaptability to uneven terrain. However, owing to the complexity in walking dynamics, disturbances introduced by terrain height variations can adversely affect the bipedal walking performance. Moreover, to generate periodic gaits, most methods require to solve the gait generation problem by using nonlinear optimization approaches, resulting in difficulties for online control. To solve this problem, this paper proposes an online gait generation method to find periodic gaits for fast walking on uneven terrain by using a pre-trained neural network. First, to enhance the terrain adaptability, this paper proposes an improved walking pattern that allows the robots to skip the last single support phase. Such improvement enlarges the feasible step region when stepping down. A compensation strategy is also proposed to reduce the velocity tracking error. Then the improved whale swarm algorithm (IWSA) is applied to generate various datasets that cover the ranges of target velocities and terrain height variations. A back-propagation (BP) network is employed to train these datasets offline to learn the gait dynamics, which is further used to generate the optimal trajectories. Simulation results suggest that, compared with the current methods, the proposed method can solve the walking return map in a short time, with improvements in both maximum walking speed and terrain adaptability.

Application of amine-loaded activated carbon fiber in CO2 capture and separation

Haoran Liu,Xinmei Lu,Liying Liu,Jian Wang,Pengyu Wang,Peng Gao,Tingsheng Ren,Guo Tian,Di Wang 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.9

The CO2 emitted by coal-fired power plants is the main factor leading to global warming, and the captureof CO2 in the flue gas of power plants is still the main task at this stage. Many adsorbents have been developed to captureCO2 in high-temperature flue gas, but some materials are complicated to synthesize or the cost is too high. Here,we used low-cost raw materials activated carbon fiber and PEI, and used green synthesis to synthesize new adsorbentsin order to capture CO2 in high-temperature flue gas of a power plant. To improve the performance of highly porousactivated carbon fiber (ACF) in CO2 capture and separation, an organic polymer polyethylenimine (PEI) was loadedsuccessfully into the oxidized ACF. The modified adsorbent was tested by FT-IR, XRD and SEM, and the CO2 adsorptioncapacity and CO2/N2 selectivity were analyzed. The results showed that the as-synthesized PEI-modified adsorbenthas a CO2 adsorption capacity of 2.5mmol/g, which is 1.7 times better than that of the pristine ACF adsorbent(1.5mmol/g), at 1 bar and 333 K, and it has excellent CO2/N2 selectivity, as calculated by ideal adsorption solution theory(IAST). These data indicate that PEI was loaded successfully into the oxidized ACF. In addition, the dual site Langmuirisotherm equation and Langmuir isotherm equation can be in good agreement with the adsorption curves ofCO2 and N2. In comparison with other composite adsorbents, the preparation process of the present new adsorbent ishighly environmentally friendly, the synthesis method is simple and the cost is low, which demonstrates potential applicationsin the separation of CO2 from the flue gas of power plants.

Mesocarbon microbead densified matrix graphite A3-3 for fuel elements in molten salt reactors

Wang, Haoran,Xu, Liujun,Zhong, Yajuan,Li, Xiaoyun,Tang, Hui,Zhang, Feng,Yang, Xu,Lin, Jun,Zhu, Zhiyong,You, Yan,Lu, Junqiang,Zhu, Libing Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.5

This study aims to provide microstructural characterization for the matrix graphite which molten salt reactors (MSRs) use, and improve resistance to molten salt infiltration of the matrix graphite for fuel elements. Mesocarbon microbeads (MCMB) densified matrix graphite A3-3 (MDG) was prepared by a quasi-isostatic pressure process. After densification by MCMBs with average particle sizes of 2, 10, and 16 ㎛, the pore diameter of A3-3 decreased from 924 nm to 484 nm, 532 nm, and 778 nm, respectively. Through scanning electron microscopy, the cross-section energy spectrum and time-of-flight secondary ion mass spectrometry, resistance levels of the matrix graphite to molten salt infiltration were analyzed. The results demonstrate that adding a certain proportion of MCMB powders can improve the anti-infiltration ability of A3-3. Meanwhile, the closer the particle size of MCMB is to the pore diameter of A3-3, the smaller the average pore diameter of MDG and the greater the densification. As a matrix graphite of fuel elements in MSR was involved, the thermal and mechanical properties of matrix graphite MDG were also studied. When densified by the MCMB matrix graphite, MDGs can meet the molten salt anti-infiltration requirements for MSR operation.

Application and optimal design of the bionic guide vane to improve the safety serve performances of the reactor coolant pump

Liu Haoran,Wang Xiaofang,Lu Yeming,Yan Yongqi,Zhao Wei,Wu Xiaocui,Zhang Zhigang 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.7

As an important device in the nuclear island, the nuclear coolant pump can continuously provide power for medium circulation. The vane is one of the stationary parts in the nuclear coolant pump, which is installed between the impeller and the casing. The shape of the vane plays a significant role in the pump's overall performance and stability which are the important indicators during the safety serve process. Hence, the bionic concept is firstly applied into the design process of the vane to improve the performance of the nuclear coolant pump. Taking the scaled high-performance hydraulic model (on a scale of 1:2.5) of the coolant pump as the reference, a united bionic design approach is proposed for the unique structure of the guide vane of the nuclear coolant pump. Then, a new optimization design platform is established to output the optimal bionic vane. Finally, the comparative results and the corresponding mechanism are analyzed. The conclusions can be gotten as: (1) four parameters are introduced to configure the shape of the bionic blade, the significance of each parameter is herein demonstrated; (2) the optimal bionic vane is successfully obtained by the optimization design platform, the efficiency performance and the head performance of which can be improved by 1.6% and 1.27% respectively; (3) when compared to the original vane, the optimized bionic vane can improve the inner flow characteristics, namely, it can reduce the flow loss and decrease the pressure pulsation amplitude; (4) through the mechanism analysis, it can be found out that the bionic structure can induce the spanwise velocity and the vortices, which can reduce drag and suppress the boundary layer separation.

Oxygen tank for synergistic hypoxia relief to enhance mitochondria-targeted photodynamic therapy

Xianghui Li,Haoran Wang,Zhiyan Li,Dandan Li,Xiaofeng Lu,Shichao Ai,Yuxiang Dong,Song Liu,Jinhui Wu,Wenxian Guan 한국생체재료학회 2022 생체재료학회지 Vol.26 No.4

Background: Mitochondria play an essential role in cellular redox homeostasis maintenance and meanwhile serve as an important target for organelle targeted therapy. Photodynamic therapy (PDT) is a promising strategy for organelle targeted therapy with noninvasive nature and highly spatiotemporal selectivity. However, the efficacy of PDT is not fully achieved due to tumor hypoxia. Moreover, aerobic respiration constantly consumes oxygen and leads to a lower oxygen concentration in mitochondria, which continuously limited the therapeutic effects of PDT. The lack of organelle specific oxygen delivery method remains a main challenge. Methods: Herein, an Oxygen Tank is developed to achieve the organelle targeted synergistic hypoxia reversal strategy, which not only act as an oxygen storage tank to open sources and reduce expenditure, but also coated with red blood cell membrane like the tank with stealth coating. Within the oxygen tank, a mitochondrion targeted photosensitizer (IR780) and a mitochondria respiration inhibitor (atovaquone, ATO) are co-loaded in the RBC membrane (RBCm) coated perfluorocarbon (PFC) liposome core. Results: Inside these bio-mimic nanoparticles, ATO effectively inhibits mitochondrial respiration and economized endogenous oxygen consumption, while PFC supplied high-capacity exogenous oxygen. These Oxygen modulators reverse the hypoxia status in vitro and in vivo, and exhibited a superior anti-tumor activity by mitochondria targeted PDT via IR780. Ultimately, the anti-tumor effects towards gastric cancer and colon cancer are elicited in vivo. Conclusions: This oxygen tank both increases exogeneous oxygen supply and decreases endogenous oxygen consumption, may offer a novel solution for organelle targeted therapies.

Ethanol Induces Autophagy Regulated by Mitochondrial ROS in Saccharomyces cerevisiae

( Hongjuan Jing ),( Huanhuan Liu ),( Lu Zhang ),( Jie Gao ),( Haoran Song ),( Xiaorong Tan ) 한국미생물 · 생명공학회 2018 Journal of microbiology and biotechnology Vol.28 No.12

Ethanol accumulation inhibited the growth of Saccharomyces cerevisiae during wine fermentation. Autophagy and the release of reactive oxygen species (ROS) were also induced under ethanol stress. However, the relation between autophagy and ethanol stress was still unclear. In this study, expression of the autophagy genes ATG1 and ATG8 and the production of ROS under ethanol treatment in yeast were measured. The results showed that ethanol stress very significantly induced expression of the ATG1 and ATG8 genes and the production of hydrogen peroxide (H₂O₂) and superoxide anion (O₂ ^·-). Moreover, the atg1 and atg8 mutants aggregated more H₂O₂ and O₂ ^·- than the wild-type yeast. In addition, inhibitors of the ROS scavenging enzyme induced expression of the ATG1 and ATG8 genes by increasing the levels of H₂O₂ and O₂ ^·-. In contrast, glutathione (GSH) and N-acetylcystine (NAC) decreased ATG1 and ATG8 expression by reducing H₂O₂ and O₂ ^·- production. Rapamycin and 3-methyladenine also caused an obvious change in autophagy levels and simultaneously altered the release of H₂O₂ and O₂ ^·-. Finally, inhibitors of the mitochondrial electron transport chain (mtETC) increased the production of H₂O₂ and O₂ ^·- and also promoted expression levels of the ATG1 and ATG8 genes. In conclusion, ethanol stress induced autophagy which was regulated by H₂O₂ and O₂ ^·- derived from mtETC, and in turn, the autophagy contributed to the elimination H₂O₂ and O₂ ^·-.

Cloning and functional characterization of two GsSnRK1 gene promoters from wild soybean

Chen Jun,Li Qiang,Zhang Pengmin,Lu Haoran,Bian Ya,Jian Yi,Wang Yizhu,Ding Xiaodong,Xiao Jialei 한국식물생명공학회 2021 Plant biotechnology reports Vol.15 No.5

Sucrose non-fermenting-related protein kinase 1 (SnRK1) belongs to a plant serine/threonine protein kinase family, and is part of a large interactive network of signaling pathways in plants to regulate many aspects of growth and development, and its gene expressions are highly responsive to multiple external stimuli. To functionally characterize the role of different SnRK1 members in wild soybean and identify the expression patterns of novel SnRK1 promoters for transgenic research, in this study, we performed an in silico analysis of the SnRK1 gene family in wild soybean and found GsSnRK1.1 and GsSnRK1.2 are main SnRK1 isoforms in wild soybean. The promoter fragments of both GsSnRK1.1 and GsSnRK1.2 were isolated, and a series of 5′-deletion and the full-length versions of both GsSnRK1.1 and GsSnRK1.2 promoters were fused with GUS reporter gene to generate expression vectors. The GUS activities in different tissues of seedling and adult growth stages of transgenic Arabidopsis plants were determined, and the GUS activities in transgenic Arabidopsis plants under NaCl, NaHCO3, PEG, ABA, MeJA and SA were also analyzed. The results showed that GsSnRK1.1 and GsSnRK1.2 genes have different expression patterns and both promoters may contain enhancers and silencers. In addition, NaCl, NaHCO3, ABA, MeJA, and PEG treatments enhanced, whereas SA treatment decreased the GUS activity under the control of both GsSnRK1.1 and GsSnRK1.2 promoters, which may be due to the distributions of various cis-elements in both GsSnRK1.1 and GsSnRK1.2 promoter regions. These results will contribute to a better understanding of the underlying mechanisms of GsSnRK1 genes in response to various abiotic stresses, and as stress-inducible promoters, GsSnRK1.1 and GsSnRK1.2 promoters can be candidates for practical application in agriculture.

Computational design towards energy efficient optimization in overconstrained robotic limbs

Gu Yuping,Wang Ziqian,Feng Shihao,Sun Haoran,Lu Haibo,Pan Jia,Wan Fang,Song Chaoyang 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.5

Legged robots are constantly evolving, and energy efficiency is a major driving factor in their design. However, combining mechanism efficiency and trajectory planning can be challenging. This work proposes a computational optimization framework for optimizing leg design during basic walking while maximizing energy efficiency. We generalize the robotic limb design as a four-bar linkage-based design pool and optimize the leg using an evolutionary algorithm. The leg configuration and design parameters are optimized based on user-defined objective functions. Our framework was validated by comparing it to measured data on our prototype quadruped robot for forward trotting. The Bennett robotic leg was advantageous for omni-directional locomotion with enhanced energy efficiency.