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A novel technique based on sub-wavelength plasma structure effects on enhancement of RF communication signals on a receiving antenna is carried out in this paper in laboratory experiments and analyzed by corresponding numerical simulations. Considerable intensification on receiving signal gain up to~10 dB in comparison with that without the plasma modulation is observed experimentally in~1 GHz RF band, with an effective enhancement bandwidth of~340 MHz and the fractional bandwidth of~34%. Then, the optimal modulation parameters of plasma are further studied by a numerical simulation. It is shown that the number density, the layer thickness, and the collision frequency of the plasma, as well as the relative distance between the plasma layer and antenna synergistically affect the modulation. Compared to the metallic antenna with the same overall dimension, the modulated antenna covered by the subwavelength plasma structure features higher receiving efficiency and lower radar cross section in the studied RF band. The mechanism of the reception enhancement is further revealed by analyzing characteristics of electromagnetic scattering and electric field distribution in the subwavelength plasma layer. The results then exhibit scientific significance and application potential of sub-wavelength plasma modulation on compact receiving antennas with higher performance and better feature of radar stealth. 相似文献
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以本源微生物菌为母菌接种于印染废水中,向改造后工艺复合生化池、接触氧化池中投加培养驯化后的复合微生物菌和生物铁填料,在稳定运行期研究了生物量、水力停留时间、溶解氧、pH、温度等因子对系统处理效果的影响,结果显示各控制因子的最佳值或范围是:在本源菌剂投加量为池有效容积的0.5%;水力停留时间复合生化池为38 h左右、接触氧化池为28 h左右;溶解氧启动初期为1.1~1.8 mg/L、稳定运行期为3.0~4.1 mg/L;调节池进水pH在9~10内;温度控制在35~38℃。在最佳处理条件下,排水口最终出水达标,出水色度13倍,去除率99.3%;出水COD 93 mg/L,去除率95.24%。 相似文献
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大气压氩等离子体射流特性 总被引:2,自引:0,他引:2
为了在大气压下获得均匀、稳定且具有较大体积的氩气介质阻挡放电等离子体射流,提出了一种新的同轴型具有螺纹型内电极结构的等离子体发生器结构设计,在大气压开放环境下获得了均匀稳定的类辉光氩气介质阻挡放电等离子体射流。实验和初步的零维数值模拟结果表明:在所研究的工作参数范围内,放电随外加电压的增加可工作于初始放电阶段、过渡阶段、稳定放电和不稳定放电阶段;在稳定放电模式下,均匀弥散的类辉光放电可充满内径为8.9mm的玻璃管,发射光谱测量结果表明在等离子体射流区含有多种化学活性粒子;数值计算和实验测量所估算的等离子体射流长度基本一致(可为30mm以上),且等离子体射流发射光谱强度的轴向分布与其中亚稳态粒子的退激发过程相关。 相似文献
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