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there are four transmission zeros and three resonant frequencies (even-mode frequency f m 1 , odd-mode frequency f m 2 , and the resonant frequency created by the parallel-coupling line). The transmission zeros T z 2 and T z 4 near the lower cutoff frequency and in the upper-stopband are attributed to the ended-coupling between the 50 X input/output feed lines. When compared with the simulated result of the filter without the loaded identical short stubs, two additional transmission zeros T z 1 and T z 3 can be generated near the upper cutoff frequency and in the lower stopband by the loaded identical short stubs, leading to sharp upper skirt and deep stopband. Simultaneity, the transmission zero T z 2 moves toward the lower cutoff frequency. EXPERIMENTAL RESULTSTo validate the above design approach, the dual-mode broadband BPF with the loaded identical short stubs is fabricated on the RT/ Duroid 5880 substrate and its photograph is shown in Figure 5. The filtering performance is measured by Agilent network analyzer N5230A. The measured |S 11 | in dB and |S 21 | in dB as well as group delay are shown in Figure 6 and illustrated good agreement with simulated results. The measured 3 dB passband is in the range of 3.19-5.84 GHz and its measured input return loss (|S 11 | in dB) is less than À14.3 dB. Three transmission zeros T z 1 , T z 2 , and T z 3 are located at 0.93, 2.39, and 6.78 GHz with an attenuation level of less than À42dB, resulting in sharp roll-off and deep lower-stopband. The upper-stopband in experiment is extended up to 9.5 GHz with an insertion loss better than À25 dB. In addition, the measured in-band group delay is varying from 0.34-0.65 ns, which is quite small and flat in all the passband. CONCLUSIONA compact broadband BPF with high selectivity is proposed using the dual-mode folded-T-type resonator and the identical short stub loaded parallel-coupling feed structure. Four transmission zeros are created near the cutoff frequencies and in the stopband by the feed structure, leading to high selectivity. A dual-mode broadband filter with the fractional bandwidth 58.89% is simulated and fabricated. The size for the resonator is only 0.156k g  0.303k g in which k g is the guided wavelength of 50 X microstrip line at 4.5 GHz. The measured results agree well with the electromagnetic (EM) simulations. When the water-drop falls into the water surface, water wave will appears. A structure will be obtained after the dispersion of waves on a water surface. In fluid dynamics, dispersion of water waves generally refers to frequency dispersion, which means that waves of different wavelengths travel at different phase speeds [5]. A photograph of water wave is shown in Figure 1. In this work, a water-wave shape, which is composed of several annuluses with different radius, is proposed. The proposed water-wave shape is convenient to be printed on the substrate [6]. ACKNOWLEDGMENTSIn this article, a novel water-wave monopole antenna is simulated, fabricated, and measured. Its characteristics, including the retu...

Hainan Island, China’s second largest island, is located in the tropics and its rivers are significantly affected by precipitation. With the construction of free trade port with Chinese characteristics, Hainan Island’s industry, agriculture, tourism and urbanization have developed in an all-round way. With the rapid development of economy, water environment ecology has been destroyed. Based on the two seasons of drought and rain, this paper took Ningyuan River and Wanquan River as the research object to study the spatial and temporal distribution of nitrogen and phosphorus nutrients in the rivers entering the sea in Hainan, and found that the concentration of nutrients in Ningyuan River was higher than that in Wanquan River. The total nitrogen pollution in dry season was higher than that in rainy season, and that in tributaries was higher than that in main stream. The maximum nitrogen content in Ningyuan River reached 2.99 mg/L and 2.37 mg/L in the dry season and rainy season, and human activities were the main reason for the increase of nutrient concentration.

Heavy metals are of wide concern due to their high toxicity, bioaccumulation and non-degradability. In this study, eight heavy metals (Cr, Mn, Ni, Cu, Zn, As, Cd, Pb) in the surface sediments of Ningyuan River were studied to investigate the distribution pattern, pollution status and potential pollution sources, and it was concluded that the concentration distribution of heavy metals in sediments is highly consistent with the population distribution pattern in space and there is a certain degree of risk of Cd pollution, and the heavy metals mainly come from mineral weathering, agricultural and shipping wastes.