A Waveguide Slot Filtering Antenna With an Embedded Metamaterial Structure

A novel waveguide slot filtering antenna with an embedded metamaterial is presented. This filtering antenna consists of a common waveguide slot antenna with longitudinal slots cut on the top broad wall of its rectangular waveguide and a metamaterial surface embedded in the bottom broad wall. The metasurface replaces the conventional metal plane in the form of a bed of nails. In the operating frequency band, the metasurface works as a perfect electric conductor, so the antenna radiates as the traditional waveguide slot antennas. While in the stopband, the metasurface performs as a perfect magnetic conductor to suppress the propagation of electromagnetic wave in the waveguide cavity, so the interference signal is rejected and a filter function is achieved. To show the design process and verify its feasibility, a filtering antenna prototype working in the C-band and having a stopband in the X-band is designed, fabricated, and tested. A good agreement between simulation and measurement is obtained, demonstrating efficient radiations in the working band and a strong suppression of more than 35 dB in the stopband

Deformation monitoring and prediction for residential areas in the Panji mining area based on an InSAR time series analysis and the GM-SVR model

Underground coal mining activities often cause ground subsidence and damage to surface construction, which seriously threatens the lives and property of residents in mining areas. In this paper, the deformation of the Yang Juzhuang village, which is a residential area in the Huainan mining area (China), was monitored through an interferometric synthetic aperture radar (InSAR) time series analysis. The vertical displacements were detected using thirteen Sentinel-1A images that were acquired between December 2016 and May 2017. The validity and applicability of the method are verified by comparing the acquired images with the GPS measurement results. Because of the deformation characteristics of the mining area, a prediction model that is combined with a grey support vector machine regression (GM-SVR) is proposed, and the practical effects of the model are verified using the deformation monitoring results of the study area. The combination of this model and SBAS-InSAR provides rapid dynamic monitoring and enables the issuance of disaster warnings in the region

Local control method and simulation analysis of hybrid AC/DC low-voltage distribution networks with high-proportion photovoltaics

Driven by the goal of energy transformation and carbon neutralization, more and more distributed photovoltaics (PVs) are integrated into low-voltage distribution networks (LVDNs). However, the integration of high-proportion PVs may lead to overload problem of distribution transformer (DT) and voltage violation problem, bringing many challenges to the safe and stable operation of LVDN. DC distribution network has the advantages of large transmission capacity and flexible power regulation, which can also realize the interconnection and power transfer between AC low-voltage lines. Therefore, structures and control methods suitable for hybrid AC/DC LVDN are proposed to alleviate the above problems caused by PVs. Firstly, the structure of hybrid AC/DC LVDN is analyzed, including the structure with parallel DC line within distribution area and the structure of DC-interconnected distribution networks between distribution areas. Secondly, a local control method of voltage source converter (VSC) is proposed for the comprehensive improvement of overload problem of DT and voltage violation problem. Finally, an actual LVDN is used to verify the effectiveness of the proposed structure and control method of hybrid AC/DC LVDN. According to the simulation results, the proposed structure of hybrid AC/DC LVDN and VSC control method can improve the voltage level and overload problems of LVDN, decrease the power loss and increase proportion of PV accommodation

Hierarchical prediction of industrial water demand based on refined Laspeyres decomposition analysis

A recent study decomposed the changes in industrial water use into three hierarchies (output, technology, and structure) using a refined Laspeyres decomposition model, and found monotonous and exclusive trends in the output and technology hierarchies. Based on that research, this study proposes a hierarchical prediction approach to forecast future industrial water demand. Three water demand scenarios (high, medium, and low) were then established based on potential future industrial structural adjustments, and used to predict water demand for the structural hierarchy. The predictive results of this approach were compared with results from a grey prediction model (GPM (1, 1)). The comparison shows that the results of the two approaches were basically identical, differing by less than 10%. Taking Tianjin, China, as a case, and using data from 2003-2012, this study predicts that industrial water demand will continuously increase, reaching 580 million m(3), 776.4 million m(3), and approximately 1.09 billion m(3) by the years 2015, 2020 and 2025 respectively. It is concluded that Tianjin will soon face another water crisis if no immediate measures are taken. This study recommends that Tianjin adjust its industrial structure with water savings as the main objective, and actively seek new sources of water to increase its supply

Treatment effect of a flavonoid prescription on duck virus hepatitis by its hepatoprotective and antioxidative ability

Context: Duck virus hepatitis (DVH) caused by duck hepatitis A virus type 1 (DHAV-1) is an acute and lethal disease of young ducklings. However, there is still no effective drug to treat DVH. Objective: This study assessed the curative effect on DVH of a flavonoid prescription baicalin-linarin-icariin-notoginsenoside R1 (BLIN) as well as the hepatoprotective and antioxidative effects of BLIN. Materials and methods: MTT method was used to test the anti-DHAV-1 ability of BLIN in vitro. We then treated ducklings by BLIN (3 mg per duckling, once a day for 5 days) to evaluate the in vivo efficacy. To study the hepatoprotective and antioxidative roles of BLIN in its curative effect on DVH, we investigated the hepatic injury evaluation biomarkers and the oxidative stress evaluation indices of the ducklings. Results: On duck embryonic hepatocytes, DHAV-1 inhibitory rate of BLIN at 20 μg/mL was 69.3%. The survival rate of ducklings treated by BLIN was about 35.5%, which was significantly higher than that of virus control (0.0%). After the treatment of BLIN, both the hepatic injury and the oxidative stress of infected ducklings alleviated. At the same time, a significant positive correlation (p < 0.05) existed between the hepatic injury indices and the oxidative stress indices. Conclusions: BLIN showed a significant curative effect on DVH. The antioxidative and hepatoprotective effects of BLIN made great contributions to the treatment of DVH. Furthermore, BLIN is expected to be exploited as a new drug for the clinical treatment of DVH