Analysis of an Impulsive One-Predator and Two-Prey System with Stage-Structure and Generalized Functional Response

An impulsive one-predator and two-prey system with stage-structure and generalized functional response is proposed and analyzed. By reasonable assumption and theoretical analysis, we obtain conditions for the existence and global attractivity of the predator-extinction periodic solution. Sufficient conditions for the permanence of this system are established via impulsive differential comparison theorem. Furthermore, abundant results of numerical simulations are given by choosing two different and concrete functional responses, which indicate that impulsive effects, stage-structure, and functional responses are vital to the dynamical properties of this system. Finally, the biological meanings of the main results and some control strategies are given

Evaluation of InSAR and TomoSAR for monitoring deformations caused by mining in a mountainous area with high resolution satellite-based SAR

Interferometric Synthetic Aperture Radar (InSAR) and Differential Interferometric Synthetic Aperture Radar (DInSAR) have shown numerous applications for subsidence monitoring. In the past 10 years, the Persistent Scatterer InSAR (PSI) and Small BAseline Subset (SBAS) approaches were developed to overcome the problem of decorrelation and atmospheric effects, which are common in interferograms. However, DInSAR or PSI applications in rural areas, especially in mountainous regions, can be extremely challenging. In this study we have employed a combined technique, i.e., SBAS-DInSAR, to a mountainous area that is severely affected by mining activities. In addition, L-band (ALOS) and C-band (ENVISAT) data sets, 21 TerraSAR-X images provided by German Aerospace Center (DLR) with a high resolution have been used. In order to evaluate the ability of TerraSAR-X for mining monitoring, we present a case study of TerraSAR-X SAR images for Subsidence Hazard Boundary (SHB) extraction. The resulting data analysis gives an initial evaluation of InSAR applications within a mountainous region where fast movements and big phase gradients are common. Moreover, the experiment of four-dimension (4-D) Tomography SAR (TomoSAR) for structure monitoring inside the mining area indicates a potential near all-wave monitoring, which is an extension of conventional InSAR

Identification of Pns6, a putative movement protein of RRSV, as a silencing suppressor

RNA silencing is a potent antiviral response in plants. As a counterdefense, most plant and some animal viruses encode RNA silencing suppressors. In this study, we showed that Pns6, a putative movement protein of Rice ragged stunt virus (RRSV), exhibited silencing suppressor activity in coinfiltration assays with the reporter green fluorescent protein (GFP) in transgenic Nicotiana benthamiana line 16c. Pns6 of RRSV suppressed local silencing induced by sense RNA but had no effect on that induced by dsRNA. Deletion of a region involved in RNA binding abolished the silencing suppressor activity of Pns6. Further, expression of Pns6 enhanced Potato virus × pathogenicity in N. benthamiana. Collectively, these results suggested that RRSV Pns6 functions as a virus suppressor of RNA silencing that targets an upstream step of the dsRNA formation in the RNA silencing pathway. This is the first silencing suppressor to be identified from the genus Oryzavirus

Interval analysis of the small‐signal stability of grid‐connected voltage‐source converter system considering multiparameter uncertainty

Abstract Grid‐connected voltage source converters (VSCs) have been broadly applied in modern power system. However, instability issues may be triggered by the integration of grid‐connected VSCs, jeopardising the operation of the power grid. Conventional stability analysis methods can be utilised to derive system stability margins under nominal conditions. Whereas grid‐connected VSCs inevitably operate under multiparameter uncertainty, which may result in overly optimistic or even incorrect estimations of stability margins, thereby posing potential risks to system operation. To address this issue, an interval small‐signal stability analysis approach is proposed to investigate the system stability under multiparameter uncertainty. First, the interval state‐space model of the grid‐connected VSC system is constructed based on interval symbolic linearisation. Furthermore, the interval eigenvalue decomposition is introduced to calculate the interval eigenvalue distribution of the interval state‐space model. Eventually, the upper bounds of the real part of the dominant interval eigenvalues are utilised for deriving interval stable parameter regions. Results of Monte Carlo analysis and time‐domain simulations of the grid‐connected VSC system are utilised to verify the effectiveness of the proposed interval stability analysis method

Distributed robust operation strategy of multi‐microgrid based on peer‐to‐peer multi‐energy trading

Abstract In microgrid (MG) systems, traditional centralised energy trading models can lead to issues such as low energy efficiency due to unstable energy supply and lack of flexibility. Peer‐to‐peer (P2P) trading models have been widely used due to their advantages in promoting the sustainable development of renewable energy and reducing energy trading costs. However, P2P multi‐energy trading requires mutual agreements between two microgrids (MGs), and the uncertainties of renewable energy and load affects energy supply security. To address these issues, this article proposed a distributed robust operation strategy based on P2P multi‐energy trading for multi‐microgrid (MMG) systems. Firstly, a two‐stage robust optimisation (TRO) method was adopted to consider the uncertainties of P2P multi‐energy trading between MGs, which reduced the conservatism of robust optimisation (RO). Secondly, a TRO model for P2P multi‐energy trading among MGs was established based on the Nash bargaining theory, where each MG negotiates with others based on their energy contributions in the cooperation. Additionally, a distributed algorithm was used to protect the privacy of each MG. Finally, the simulation results based on three MGs showed that the proposed approach can achieve a fair distribution of cooperative interests and effectively promote cooperation among MGs

Static Compressive Properties of Polypropylene Fiber Foam Concrete with Concave Hexagonal Unit Cell

For the purpose of studying the influence of fiber on the negative Poisson’s ratio effect of foam concrete, a concave hexagonal unit cell structure of polypropylene fiber foam concrete was proposed. The effects of different fiber volume contents on the structural mechanical parameters, Poisson’s ratio, and energy absorption capacity of the unit cells were studied by static compression of concave hexagonal unit cells and cube specimens. The results show that the compressive strength of foam concrete is reduced by adding polypropylene fiber, and the peak stress of concave hexagonal unit cells decreases less rapidly than that of cube specimens. The proper amount of polypropylene fiber can enhance the deformation ability of the unit cells in foam concrete, and the Poisson’s ratio of the unit cells in foam concrete with 1.5% fiber content is the lowest. In the process of failure of concave hexagonal unit cells, the failure phenomenon is mainly concentrated on the concave surfaces on both sides, and the cracks are distributed in the form of “upper left and lower right” or “lower left and upper right”. When the content of polypropylene fiber is 0.5%, the total energy absorbed by the concave hexagonal cells in the compression deformation process increases by 12.98%

Surface Modification of GdMn₂O₅ for Catalytic Oxidation of Benzene via a Mild A-Site Sacrificial Strategy

Thermal catalytic oxidation technology is an effective way to eliminate refractory volatile organic pollutants, such as Benzene. Nevertheless, a high reaction temperature is usually an obstacle to practical application. Here, GdMn2O5 mullite (GMO-H) catalyst with disordered surface Gd-deficient and oxygen-vacancy-rich concentrations was synthesized via a controllable low-temperature acid-etching route. Results show that the preferentially broken Gd-O bond is conducive to exposing more Mn-Mn active sites, which Gd species covered. The affluent surface oxygen vacancies supply sufficient adsorption sites for oxygen molecules, facilitating the oxygen cycles during Benzene catalytic oxidation. Furthermore, surface exposed Mn3+ species were oxidized to Mn4+, which is beneficial to increase catalytic activity at a lower temperature. Compared with the conventional GdMn2O5, the reaction temperature for removing 90% Benzene over GMO-H was dropped from 405 to 310 °C with WHSV of 30,000 mL g−1 h−1. Significantly, during a 72 h catalytic test, the catalytic activity remains constant at 90% of the Benzene removal at 300 °C, indicating excellent activity stability. This work reported an efficient approach to preparing manganese-base mullite thermal catalyst, providing insight into the catalytic oxidation of Benzene

Surface Modification of GdMn2O5 for Catalytic Oxidation of Benzene via a Mild A-Site Sacrificial Strategy

Thermal catalytic oxidation technology is an effective way to eliminate refractory volatile organic pollutants, such as Benzene. Nevertheless, a high reaction temperature is usually an obstacle to practical application. Here, GdMn2O5 mullite (GMO-H) catalyst with disordered surface Gd-deficient and oxygen-vacancy-rich concentrations was synthesized via a controllable low-temperature acid-etching route. Results show that the preferentially broken Gd-O bond is conducive to exposing more Mn-Mn active sites, which Gd species covered. The affluent surface oxygen vacancies supply sufficient adsorption sites for oxygen molecules, facilitating the oxygen cycles during Benzene catalytic oxidation. Furthermore, surface exposed Mn3+ species were oxidized to Mn4+, which is beneficial to increase catalytic activity at a lower temperature. Compared with the conventional GdMn2O5, the reaction temperature for removing 90% Benzene over GMO-H was dropped from 405 to 310 °C with WHSV of 30,000 mL g−1 h−1. Significantly, during a 72 h catalytic test, the catalytic activity remains constant at 90% of the Benzene removal at 300 °C, indicating excellent activity stability. This work reported an efficient approach to preparing manganese-base mullite thermal catalyst, providing insight into the catalytic oxidation of Benzene