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21.
摘要:针对水下无线传感网络中运动节点定位精度低的问题,提出了一种新的基于双层修正无迹卡尔曼的水下节点定位算法(DLMUKF)。该算法利用下层无迹卡尔曼滤波算法对节点状态进行预测,根据各信标节点的测距传播时延对预测的节点状态进行修正。运用上层无迹卡尔曼滤波算法对修正后的状态进行新的预测与修正。仿真实验中,DLMUKF算法的平均定位误差约为传统多边定位算法的15%,约为基于无迹卡尔曼滤波(UKF)定位算法的16%,受节点运动时间与速度的影响最小。通过实验证明DLMUKF算法能更充分利用实际距离值,可以有效减小运动节点的定位误差。 .txt 相似文献
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23.
目前,德国纺织机械和高性能材料技术研究所(ITM)正对刨花金属短纤维纺制纱线的工艺过程进行广泛的调查研究。为顺利纺纱,必须考虑这类纤维的高耐磨性、高脆性和高刚性等特性,以及它们较高的塑性变形和粘滑运动倾向。基于传统成纱工艺,开发出以刨花金属短纤维为原料,经拉伸断裂、牵伸和纺纱过程制备纯金属纱线的纺纱工艺链。基于目前的研究,由刨花金属短纤维制备纯金属纱线的可行性已得以证实。所得金属纤维在高性能、低成本技术应用方面具有较高的潜力。 相似文献
24.
Yuanbo LI 《等离子体科学和技术》2019,21(9):95601-131
To implement on-line, real-time monitoring for the surface morphology of Plasma-Facing Materials (PFMs) in tokamak, we developed a Laser Speckle Interferometry measurement approach. A laser ablation method was used to simulate the erosion process during Plasma-Wall Interactions in a tokamak. In the present investigation, we evaluated the results of laser ablation morphology changes on the surface of Mo material reconstructed by four different approaches (Flood-fill, Quality-guided, Discrete Cosine Transform (DCT) and Weighted-DCT). The morphology results measured by the weighted-DCT approach are very close to the measurement results from confocal microscopy with an average error rate within 7%. It is verified that the weighted-DCT algorithm has high accuracy and can efficiently reduce the influence of noise pollution coming from laser ablation, which is used as a proxy for erosion from plasma wall interaction. Additionally, the CPU computer time has been shortened. This is of great significance for the real-time monitoring of PFMs’ morphology in the Experimental Advanced Superconducting Tokamak (EAST) in the future. 相似文献
25.
Zeyu HAO 《等离子体科学和技术》2019,21(7):75401-118
The effects of driving frequency on plasma parameters and electron heating efficiency are studied in cylindrical inductively coupled plasma (ICP) source. Measurements are made in an Ar discharge for driving frequency at 13.56/2 MHz, and pressures of 0.4–1.2 Pa. In 13.56 MHz discharge, higher electron density (ne) and higher electron temperature (Te) are observed in comparison with 2 MHz discharge at 0.6–1.2 Pa. However, slightly higherne andTe are observed in 2 MHz discharge at 0.4 Pa. This observation is explained by enhanced electron heating efficiency due to the resonance between the oscillation of 2 MHz electromagnetic field and electron-neutral collision process at 0.4 Pa. It is also found that the variation ofTe distribution is different in 13.56 and 2 MHz discharge. For ICP at 13.56 MHz, Te shows an edge-high profile at 0.4–1.2 Pa. For 2 MHz discharge,Te remains an edge-high distribution at 0.4–0.8 Pa. However, the distribution pattern involves into a center-high profile at 0.9–1.2 Pa. The spatial profiles ofne remain a center-high shape in both 13.56 and 2 MHz discharges, which indicates the nonlocal kinetics at low pressures. Better uniformity could be achieved by using 2 MHz discharge. The effects of gas pressure on plasma parameters are also examined. An increase in gas pressure necessitates the rise ofne in both 13.56 and 2 MHz discharges. Meanwhile, Te drops when gas pressure increases and shows a flatter distribution at higher pressure. 相似文献
26.
Tao ZHU 《等离子体科学和技术》2019,21(4):44006-51
In this paper, narrow-pulse power discharge is used to study the synergistic control of mercury and dioxins, in which 1,2,4-trichlorobenzene (TCB) was used as a dioxin analog, by using a self- designed experimental system. The competitive effects of NO, SO2 and HCl on the TCB removal by non-thermal plasma are discussed. The influence of acid gas on TCB degradation is reflected in the competitive effect. NO has the greatest influence on TCB degradation efficiency. The oxidation efficiency of Hg0 decreased by about 10% in all three acidic gas atmospheres, and the effect of each gas component on Hg0 oxidation is complex. In the flue gas atmosphere of ‘acid gas+Hg0 +TCB’, the mechanism of the synergistic control of Hg0 and TCB by the non- thermal plasma is different, which has competition and promotion relationship between each other. The contribution of various flue gas components to the results was complicated, but the overall experimental results show that the synergistic control effect of the system can continue to improve. According to the generated product backstepping, ·OH plays an important role in the synergistic control of the degradation of Hg0 and TCB. Through this study, we hope to provide basic research data for the collaborative control of flue gas in the incineration industry. 相似文献
27.
Fubao JIN 《等离子体科学和技术》2019,21(5):54002-22
Due to the complexity of the valve side winding voltage of the converter transformer, the insulation characteristics of the oil-impregnated pressboard (OIP) of the converter transformer are different from those of the traditional AC transformer. The study on effect of temperature on the creeping discharge characteristics of OIP under combined AC–DC voltage is seriously inadequate. Therefore, this paper investigates the characteristics of OIP creepage discharge under combined AC–DC voltage and discusses the influence of temperature on creepage discharge characteristics under different temperatures from 70°C to 110 °C. The experimental results show that the partial discharge inception voltage and flashover voltage decrease with increasing temperature. The times of low amplitude discharge (LAD) decrease and amplitude of LAD increases. Simultaneously, the times of high amplitude discharge (HAD) gradually increase at each stage of creepage discharge with higher temperature. The analysis indicates that the charge carriers easily accumulate and quickly migrate directional movement along the electric field ahead of discharging. The residual charge carriers are more easily dissipated after discharging. The ‘hump’ region of LAD moves to the direction of higher discharge magnitude. The interval time between two continuous discharges is shortened obviously. The concentration of HAD accelerates the development of OIP insulation creepage discharge. The temperature had an accelerating effect on the development of discharge in the OIP under applying voltage. 相似文献
28.
Libin LV 《等离子体科学和技术》2019,21(9):95301-57
In this study, we present a simulation study of artificial field-aligned irregularities (AFAI) to calculate the scattering coefficient considering a Gaussian autocorrelation function for the wave number spectrum of the density fluctuation. By analyzing variations in the scattering coefficient under different ionospheric backgrounds, the optimal range of the heating frequency was found, which is about 0.9–1 times the critical frequency of the F2 layer. This is especially noticeable as when the heating frequency varies from 0.5 times to 0.9 times of the critical frequency, the scattering coefficient increases by 6.8–16.2 dB. These results should be useful for optimizing the heating frequency in the future artificial field-aligned scattering (AFAS) transmission applications at middle and low latitudes. 相似文献
29.
Tarek Uddin MOHAMMED Aziz Hasan MAHMOOD Mohammad Zunaied-Bin-HARUN Jamil Ahmed JOY Md. Asif AHMED 《Frontiers of Structural and Civil Engineering》2021,15(6):1400
Aggregates are the biggest contributor to concrete volume and are a crucial parameter in dictating its mechanical properties. As such, a detailed experimental investigation was carried out to evaluate the effect of sand-to-aggregate volume ratio (s/a) on the mechanical properties of concrete utilizing both destructive and non-destructive testing (employing UPV (ultrasonic pulse velocity) measurements). For investigation, standard cylindrical concrete samples were made with different s/a (0.36, 0.40, 0.44, 0.48, 0.52, and 0.56), cement content (340 and 450 kg/m3), water-to-cement ratio (0.45 and 0.50), and maximum aggregate size (12 and 19 mm). The effect of these design parameters on the 7, 14, and 28 d compressive strength, tensile strength, elastic modulus, and UPV of concrete were assessed. The careful analysis demonstrates that aggregate proportions and size need to be optimized for formulating mix designs; optimum ratios of s/a were found to be 0.40 and 0.44 for the maximum aggregate size of 12 and 19 mm, respectively, irrespective of the W/C (water-to-cement) and cement content. 相似文献
30.
Pratik P. BHATT Venkatesh K. R. KODUR Anuj M. SHAKYA Tarek ALKHRDAJI 《Frontiers of Structural and Civil Engineering》2021,15(1):177
This paper presents the results of fire resistance tests on carbon fiber-reinforced polymer (CFRP) strengthened concrete flexural members, i.e., T-beams and slabs. The strengthened members were protected with fire insulation and tested under the combined effects of thermal and structural loading. The variables considered in the tests include the applied load level, extent of strengthening, and thickness of the fire insulation applied to the beams and slabs. Furthermore, a previously developed numerical model was validated against the data generated from the fire tests; subsequently, it was utilized to undertake a case study. Results from fire tests and numerical studies indicate that owing to the protection provided by the fire insulation, the insulated CFRP-strengthened beams and slabs can withstand four and three hours of standard fire exposure, respectively, under service load conditions. The insulation layer impedes the temperature rise in the member; therefore, the CFRP–concrete composite action remains active for a longer duration and the steel reinforcement temperature remains below 400°C, which in turn enhances the capacity of the beams and slabs. 相似文献