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The study addresses path planning problems for autonomous mobile robots (AMRs), considering their kinematics, where performance and responsiveness are often incompatible. This study proposes a multi-agent policy learning-based method to tackle this challenge in dynamic environments. The proposed method features a centralized learning and decentralized execution-based path planning framework designed to meet performance and responsiveness requirements. The problem is modeled as a partial observation Markov Decision Process for policy learning while considering the kinematics using conventional neural networks. Then, an improved proximal policy optimization algorithm is developed with highlight experience replay that corrects failed experiences to speed up the learning processes. The experimental results show that the proposed method outperforms the baselines in both static and dynamic environments. The proposed method shortens the movement distance and time in static environments by about 29.1% and 5.7%, as well as in dynamic environments by about 21.1% and 20.4%, respectively. The runtime is maintained in milliseconds across various environments, taking only 0.07 s. Overall, the proposed method is valid and efficient in ensuring the performance and responsiveness of AMRs when dealing with complex and dynamic path planning problems. [ABSTRACT FROM AUTHOR]

Quercetin is one of the main flavonoids in the human diet and mainly found in different plant tissues, including seeds, flowers, leaves, stems, and roots. However, its biological function in plant tissues, especially in seeds, is unknown. In this study, the seed germination and subsequent seedling growth of Apocynum pictum and A. venetum under osmotic stress (400 mmol L−1 mannitol) supplemented with 5 μmol L−1 quercetin were evaluated after 7, 14, and 21 days of germination. Results showed that quercetin improved the germination percentage and seed vigor, as indicated by the higher germination energy, shoot length, root length, dry weight, fresh weight, and chlorophyll content in A. pictum and A. venetum seedlings under the mannitol compared with those under the mannitol alone. Quercetin decreased H 2 O 2 and O 2 − production and cell membrane damage, and mostly increased the gene expression of superoxide dismutase, peroxidase, catalase, chalcone synthase and flavonol synthase in A. pictum and A. venetum seedlings under the mannitol compared with those under the mannitol alone. In addition, the germination energy of A. pictum was 21.57% higher than that of A. venetum , and the gene expression of key enzymes in quercetin biosynthesis in A. pictum was mostly higher than that in A. venetum after 1 and 7 days of germination. These results indicated that quercetin was an effective anti-osmotic agent that alleviated the adverse effect of mannitol-induced osmotic stress on seed germination and seed vigor, and A. pictum seeds were more osmotic resistant than A. venetum seeds. Quercetin supplement alleviated the adverse impact of osmotic stress on seed germination and seed vigor in A. pictum and A. venetum by decreasing ROS production and cell membrane damage, and enhancing antioxidant enzyme activity, photosynthesis, and quercetin biosynthesis. Image 1 • Quercetin enhanced the seed germination and seed vigor under osmotic stress. • A. pictum seeds were more osmotic resistant than A. venetum seeds. [ABSTRACT FROM AUTHOR]

The development of smart factories has put forward more flexible logistics needs for automobile assembly system, and efficient scheduling strategies to meet these requirements still demand prompt solution. Thus, this paper focuses on the problem of materials distribution with automated guided vehicles (AGVs) in automobile assembly lines. The mathematical model is established in the light of actual situation with mixed time windows and an improved genetic algorithm (GA) is developed. Considering the demand characteristics both in time and space, material demand points are clustered based on their spatiotemporal distance to generate the initial population. Then, selection, crossover and mutation operators of GA are also ameliorated as necessary to minimize the total travel cost. Finally, practical examples are carried out to demonstrate the effectiveness of this methodology. [ABSTRACT FROM AUTHOR]

Photocatalytic oxidation removal of elemental mercury (Hg 0 ) by Ag@AgCl/Ag 2 CO 3 hybrids was carried out in a wet scrubbing reactor under fluorescent light. The photocatalysts synthesized via a modified coprecipitation method were characterized by using SEM-EDS, HRTEM, N 2 adsorption-desorption, XRD, XPS, DRS, and ESR. Effects of operational parameters on Hg 0 removal, including AgCl content, fluorescent light (FSL) irradiation, pH value, reaction temperature, and flue gas components (O 2 , SO 2 and NO) were studied in detail. Furthermore, simultaneous removal of Hg 0 and SO 2 was investigated and the possible mechanism of highly enhanced Hg 0 removal efficiency was proposed. The results showed that AgCl amount, fluorescent light irradiation, reaction temperature, SO 2 and NO had notable impact on Hg 0 removal efficiency. Simultaneous removal efficiencies of 98% for SO 2 and 80% for Hg 0 were obtained by coupling Ag@AgCl(0.3)/Ag 2 CO 3 with Ca(OH) 2 under FSL. The trapping studies of reactive radicals exhibited that holes (h + ) were one of the main reactive species for Hg 0 removal. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe-doped MoS 2 nanosheets are prepared via one-pot hydrothermal route. • Nanozymes can exhibit controllable catalysis depending on Mo-to-Fe molar ratios. • Doped Fe atoms and Mo-S sites may conduct synergistic effects on the improved catalysis. • Two different catalytic pathways are proposed for Fe-MoS 2 nanozyme by kinetic studies. • Bi-catalysts-based colorimetric platform is developed for probing glucose in blood. MoS 2 nanosheets were doped with Fe elements simply via the one-pot hydrothermal route resulting in the peroxidase-like nanozymes with dramatically enhanced catalysis. It was discovered that the resulted Fe-MoS 2 could display controllable catalysis activities depending on the Mo-to-Fe molar ratios, among which the highest one was achieved at 3/1 with catalysis efficiency over three folds higher than that of pristine MoS 2. The greatly improved catalysis performances of Fe-MoS 2 nanozyme are thought to be resulted from the synergistic effects of the doped Fe atom and Mo-S sites. On the one hand, herein, the Fe sites might serve as the electron transferring mediators to facilitate the peroxidase-like catalytic reactions, as confirmed by the cytochrome C -based electron transportation experiments. On the other hand, the Mo-S sites might conduct the catalytic behavior of Fenton-like reactions, as revealed by the hydroxyl radicals-capturing experiments. Furthermore, the feasibility of practical applications for the developed Fe-MoS 2 nanozyme based colorimetric methods was demonstrated for glucose in blood sample. Importantly, an insight can be thereby obtained into the design of different nanozymes with enhanced catalysis designed by doping heteroatoms like Fe, promising for the catalysis-based applications in the biomedical analysis, food safety, and environmental monitoring fields. [ABSTRACT FROM AUTHOR]

• Static coarsening behavior was controlled by termination migration and Ostwald ripening mechanism. • The average diameter of Ti 2 Cu phase increased with thermal exposure time. • The loss of ductility is mainly attributed to the coarsening of Ti 2 Cu phase. [Display omitted] The static coarsening behavior of a Ti-14Cu alloy relative to the Ti 2 Cu phase after long-term isothermal thermal exposure was comprehensively investigated. The growth of the precipitated phase is shown to be controlled by the diffusion mechanism characterized by morphological variation during thermal exposure. The static coarsening process is composed of a rapid coarsening stage and stable coarsening stage, and it is primarily governed by volume diffusion of the Lifshitz-Slyozov-Wagner (LSW) model. The rapid coarsening stage is mainly dominated by the terminal migration mechanism, while the stable coarsening stage is governed by the Ostwald ripening mechanism. The rapid coarsening of the Ti 2 Cu phase enhances the effects of precipitation strengthening significantly and simultaneously improves the plasticity of the alloy. However, with stable coarsening, the presence of the high-volume Ti 2 Cu phase in a Ti-14Cu alloy increases the effective slip length during deformation and reduces plasticity. [ABSTRACT FROM AUTHOR]

Abstract: In this article AVR and PSS are integrated with generator, and constituted the complete object-oriented model included generator and its controllers. By means of energy composition of analog circuit, controller AVR and PSS equivalent energy function descriptions are obtained. Then controller energy functions are added to the generator Hamiltonian function, and composed the total energy function of system. Furthermore, a Hamiltonian model of generator integrated AVR and PSS is derived. Finally, according to the dissipative properties of Hamiltonian model, AVR and PSS influences on generator system dissipative properties are analyzed, and PSS damping effect on port is discussed. The results show that damping characteristics reflected in the model are consistent with practical system. [Copyright &y& Elsevier]

Abstract: Hamiltonian function is different, the internal structure relation given by generalized Hamiltonian model is different, and thus Hamiltonian function is core issue for generalized Hamiltonian modeling. In this paper, three principles of selecting Hamiltonian function are proposed, interface principle, energy principle and stability principle. For the class of system with single input and single output, applied methods of three principles are given. At last, the Hamiltonian modelling for nonlinear hydro turbine is taken as case to introduce its application. [Copyright &y& Elsevier]

Abstract: Generalized Hamiltonian model can give dynamics mechanism of inner parameters connected, however, it will meet many difficult while an actual physical system is converted to Generalized Hamiltonian model. And due to complexity of the structure matrix and damping matrix of high order Hamiltonian system, analysis and application to inner parameters connected mechanism is not ease and convenience. In this paper one kind of Hamiltonian model, four order and single input affine nonlinear system, is given basic form, it is a formulation formulize form, that is generalize Hamiltonian model can be directly derived by formulate calculation. The hydro turbine Hamiltonian model is taken as case to introduce this modeling method. At last, a simulation simplified method based-physical background is proposed, and used to simplify the hydro turbine Hamiltonian model. [Copyright &y& Elsevier]

Abstract: One of key means on study coupling relationship between hydraulic system and electromechanical system is that build the corresponding relationship between guide vane motion and disturbance occurred by hydro turbine generating units and power network, that is called as tracking response characteristics of guide vane. This paper analyzes the basic characteristics and mathematic model of guide vane motion based on classic structure hydro turbine generating units model, in which include governor, excitation controller, hydro turbine and generator, and simulates guide vane motion in practical operating. At last, the active power regulations are simulated. According to simulation curves, build tracking response model of guide vane to active power regulation, and define tracking characteristic coefficients and give its calculation method. Simulation results show that proposed tracking model has well self-adaptive ability due to include basic motion characteristics and is effective. [Copyright &y& Elsevier]

Abstract: The water flow in turbine flow passage is one of the prime reasons that lead to the vibration of the spiral casing structure of large-scale hydropower station, and the fluid-structure interaction of the spiral casing structure is very complex. In this study, a numerical method it presented, which could simulate the vibration of spiral casing structure that caused by the water flow in turbine flow passage. The numerical simulation of 3-D unsteady turbulent flow through the flow passage of turbine model is accomplished by solving the N-S equations, and the flow fields of flow passage and dynamic water pressure on boundary are obtained. At the same time, the three-dimension finite element dynamic model of solid structure is established, which contain steel liner and concrete surrounding the spiral case. And then, the three-dimensional instantaneous analysis of solid are proceeded as well as the dynamic water pressure transfer real-time by user interface program on interface at which the fluid interacts with solid. The one-way coupling analysis between fluid and solid structure is realized, through which the stress field and displacement field of solid induced by water flow are obtained. At last, a case study of a spiral casing structure which located in a hydropower station in Yunnan Province is presented. [Copyright &y& Elsevier]

Abstract: A double shell-potential flow model is developed to study the free vibration of the water-filled single-walled carbon nanotubes (SWCNTs) in the paper. SWCNTs are coupled with inner water via the van der Waals (vdW) interaction. It is shown that the vdW forces upshift the frequency of the SWCNTs. The results also reveal that the internal moving fluid plays an important role in the instability of system whereas the fluid velocity has very little influence on the dynamic characteristics of the tube. [Copyright &y& Elsevier]

Abstract: The parts of hydro-turbine and its stability is often damaged and affected by the vibration and this often results in great loss. The reason of vibration is various. Based on a real machine in laboratory, this paper uses ANSYS finite element software to model the main shaft system in the hydro-turbine generating unit. On this basis, it takes the modal analysis and calculates the critical speed of rotation. The results can provide a reference for dynamic analysis and a foundation for the design or improvement. [Copyright &y& Elsevier]