scholarly journals Modeling of the Marine atmosphere and its impact on Ka-band channels

2022 ◽  
Vol 355 ◽  
pp. 03046
Author(s):  
Zheng Liu ◽  
Fu-an Sun ◽  
Bin Zhou
Keyword(s):  
Rainfall Intensity ◽  
Elevation Angle ◽  
Estimation Method ◽  
Atmospheric Environment ◽  
Marine Atmosphere ◽  
Frequency Channel ◽  
Ka Band ◽  
Variation Characteristics ◽  
Attenuation Models ◽  
Atmosphere Environment

The sea atmosphere environment will affect the Ka frequency channel in TT&C. Firstly, this paper briefly introduces the Marine atmospheric environment. Attenuation models of water vapor solubility and rainfall intensity are established. The variation characteristics of atmospheric environment and the estimation method of rainfall intensity are studied. Finally, the influence of Marine atmosphere on Ka-band channel is simulated and analyzed. The simulation results show that different elevation angles have different effects on Ka-band channels. The influence result decreases gradually with the elevation Angle increasing.

scholarly journals Corrosion Behavior and Mechanical Properties of 30CrMnSiA High-Strength Steel under an Indoor Accelerated Harsh Marine Atmospheric Environment

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 629
Author(s):  
Ning Li ◽  
Weifang Zhang ◽  
Hai Xu ◽  
Yikun Cai ◽  
Xiaojun Yan
Keyword(s):  
Mechanical Properties ◽  
Corrosion Behavior ◽  
High Strength Steel ◽  
High Strength ◽  
Atmospheric Environment ◽  
Composition Analysis ◽  
Marine Atmosphere ◽  
Rust Layer ◽  
The Matrix ◽  
Atmosphere Environment

In this work, the corrosion behavior and mechanical properties of 30CrMnSiA high-strength steel under a harsh marine atmosphere environment were systematically studied using accelerated test technology, along with corrosion kinetic analysis, microstructure and phase composition analysis, electrochemical measurements, and mechanical property tests. The influence of corrosion time on corrosion kinetics was characterized by the weight loss method. The corrosion layer and its product evolution were analyzed by SEM, EDS, XRD, and XPS. The corrosion behavior of steel was studied by a potentiodynamic polarization curve and EIS. Finally, the influence of corrosion on mechanical properties was studied by tensile and fatigue tests. The results show that 30CrMnSiA high strength steel has good corrosion resistance in a harsh marine atmosphere environment. Its corrosion behavior is cyclical: the outer rust layer exfoliated, the inner rust layer became the outer rust layer, and the matrix became inner rust due to the attack by the corrosive medium. The rust layer had a great protective effect on the matrix. The mechanical properties of 30CrMnSiA high-strength steel were reduced under the corrosive environment, and corrosion had a significant effect on its fatigue resistance.

scholarly journals Retrieval of Fine-Resolution Aerosol Optical Depth (AOD) in Semiarid Urban Areas Using Landsat Data: A Case Study in Urumqi, NW China

2020 ◽  
Vol 12 (3) ◽  
pp. 467 ◽  
Author(s):  
Xiangyue Chen ◽  
Jianli Ding ◽  
Jingzhe Wang ◽  
Xiangyu Ge ◽  
Mayira Raxidin ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Urban Areas ◽  
Lookup Table ◽  
Atmospheric Environment ◽  
Sustainable Urban Development ◽  
Long Distance ◽  
Hysplit Model ◽  
Variation Characteristics ◽  
Fine Resolution

The aerosol optical depth (AOD) represents the light attenuation by aerosols and is an important threat to urban air quality, production activities, human health, and sustainable urban development in arid and semiarid regions. To some extent, the AOD reflects the extent of regional air pollution and is often characterized by significant spatiotemporal dynamics. However, detailed local AOD information is ambiguous at best due to limited monitoring techniques. Currently, the availability of abundant satellite data and constantly updated AOD extraction algorithms offer unprecedented perspectives for high-resolution AOD extraction and long-time series analysis. This study, based on the long-term sequence MOD09A1 data from 2010 to 2018 and lookup table generation, uses the improved deep blue algorithm (DB) to conduct fine-resolution (500 m) AOD (at 550 nm wavelength) remote sensing (RS) estimation on Landsat TM/OLI data from the Urumqi region, analyzes the spatiotemporal AOD variation characteristics in Urumqi and combines gray relational analysis (GRA) and the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to analyze AOD influence factors and simulate pollutant propagation trajectories in representative periods. The results demonstrate that the improved DB algorithm has a high inversion accuracy for continuous AOD inversion at a high spatial resolution in urban areas. The spatial AOD distribution in Urumqi declines from urban to suburban areas, and higher AODs are concentrated in cities and along roads. Among these areas, Xinshi District has the highest AOD, and Urumqi County has the lowest AOD. The seasonal AOD variation characteristics are distinct, and the AOD order is spring (0.411) > summer (0.285) > autumn (0.203), with the largest variation in spring. The average AOD in Urumqi is 0.187, and the interannual variation generally shows an upward trend. However, from 2010 to 2018, AOD first declined gradually and then declined significantly. Thereafter, AOD reached its lowest value in 2015 (0.076), followed by a significant AOD increase, reaching a peak in 2016 (0.354). This shows that coal to natural gas (NG) project implementation in Urumqi promoted the improvement of Urumqi’s atmospheric environment. According to GRA, the temperature has the largest impact on the AOD in Urumqi (0.699). Combined with the HYSPLIT model, it was found that the aerosols observed over Urumqi were associated with long-range transport from Central Asia, and these aerosols can affect the entire northern part of China through long-distance transport.

scholarly journals Characterization of Rain Specific Attenuation and Frequency Scaling Method for Satellite Communication in South Korea

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Sujan Shrestha ◽  
Dong-You Choi
Keyword(s):  
South Korea ◽  
Satellite Communication ◽  
Rain Rate ◽  
Rain Attenuation ◽  
Frequency Scaling ◽  
Scaling Method ◽  
Ka Band ◽  
Specific Attenuation ◽  
Rain Specific Attenuation ◽  
Attenuation Models

The attenuation induced by rain is prominent in the satellite communication at Ku and Ka bands. The paper studied the empirical determination of the power law coefficients which support the calculation of specific attenuation from the knowledge of rain rate at Ku and Ka band for Koreasat 6 and COMS1 in South Korea that are based on the three years of measurement. Rain rate data was measured through OTT Parsivel which shows the rain rate of about 50 mm/hr and attenuation of 10.7, 11.6, and 11.3 dB for 12.25, 19.8, and 20.73 GHz, respectively, for 0.01% of the time for the combined values of rain rate and rain attenuation statistics. Comparing with the measured data illustrates the suitability for estimation of signal attenuation in Ku and Ka band whose validation is done through the comparison with prominent rain attenuation models, namely, ITU-R P.618-12 and ITU-R P. 838-3 with the use of empirically determined coefficient sets. The result indicates the significance of the ITU-R recommended regression coefficients of rain specific attenuation. Furthermore, the overview of predicted year-wise rain attenuation estimation for Ka band in the same link as well as different link is studied which is obtained from the ITU-R P. 618-12 frequency scaling method.

scholarly journals Precipitation Estimates from Commercial Microwave Links: Practical Approaches to Wet-antenna Correction

2021 ◽  
Author(s):  
Jaroslav Pastorek ◽  
Martin Fencl ◽  
Jörg Rieckermann ◽  
Vojtěch Bareš
Keyword(s):  
Rainfall Intensity ◽  
Rain Gauge ◽  
Model Parameters ◽  
Rainfall Events ◽  
Precipitation Estimates ◽  
Attenuation Models ◽  
Using Data ◽  
Quantitative Precipitation Estimates ◽  
Rain Gauge Network ◽  
Commercial Microwave Links

An inadequate correction for wet antenna attenuation (WAA) often causes a notable bias in quantitative precipitation estimates (QPEs) from commercial microwave links (CMLs) limiting the usability of these rainfall data in hydrological applications. This paper analyzes how WAA can be corrected without dedicated rainfall monitoring for a set of 16 CMLs. Using data collected over 53 rainfall events, the performance of six empirical WAA models was studied, both when calibrated to rainfall observations from a permanent municipal rain gauge network and when using model parameters from the literature. The transferability of WAA model parameters among CMLs of various characteristics has also been addressed. The results show that high-quality QPEs with a bias below 5% and RMSE of 1 mm/h in the median could be retrieved, even from sub-kilometer CMLs where WAA is relatively large compared to raindrop attenuation. Models in which WAA is proportional to rainfall intensity provide better WAA estimates than constant and time-dependent models. It is also shown that the parameters of models deriving WAA explicitly from rainfall intensity are independent of CML frequency and path length and, thus, transferable to other locations with CMLs of similar antenna properties.

scholarly journals Ultrawideband Discharge Source DOA Estimation Method Using Multiple Baseline Wideband Time-Domain Interferometry with Hilbert Transform

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Jiangzehui Yan ◽  
Luping Xu ◽  
Chunhua Li ◽  
Weihao Tie ◽  
Xuerong Sun
Keyword(s):  
Hilbert Transform ◽  
Time Domain ◽  
Elevation Angle ◽  
Estimation Method ◽  
Doa Estimation ◽  
Azimuth Angle ◽  
Location Estimation ◽  
Multiple Baseline ◽  
Baseline Length ◽  
Discharge Source

The research interest of ultrawideband (UWB) discharge source location estimation has increased these years. In this paper, a direction of arrival (DOA) estimation method using multiple baseline wideband time-domain interferometry with Hilbert transform for UWB discharge source is proposed based on time-domain and frequency-domain characteristics of radiated RF electromagnetic pulses (EMPs) from discharge sources. Monte Carlo simulations are then carried out; the results indicate that, the proposed method provides a better performance in UWB discharge source DOA estimation than the traditional time-domain method, especially in low signal-to-noise ratio (SNR) conditions. Moreover, the influences of antenna array configurations and incident angles of radiated EMPs on the estimation precision are also studied. It has been shown that, the accuracy of both elevation angle and azimuth angle estimation improves with the increase of the antenna element number and baseline length. As for the influence of incident angles, the estimation accuracy of elevation angle enhances when real elevation angle increases, while that of azimuth angle tends to be opposite. Meanwhile, the real azimuth angle has little effect on the DOA estimation. Finally, an experimental setup for discharge source DOA estimation is introduced and the experiment results are illustrated.

The Selection of Transmitter Elevation in a Ka-Band HAP-Based Communication System under Fog Attenuation

2014 ◽  
Vol 687-691 ◽  
pp. 3709-3713
Author(s):  
Jian Yun Zheng ◽  
Niu Hai ◽  
Yi Sheng Zhu
Keyword(s):  
Liquid Water ◽  
Communication System ◽  
Elevation Angle ◽  
Numerical Results ◽  
Water Density ◽  
Approximation Model ◽  
Ka Band ◽  
Rayleigh Approximation ◽  
Selection Of

The Rayleigh approximation model is used for analyzing fog attenuation of the HAP-based communication system, the influence of transmitter elevation to fog attenuation under different temperature and liquid water density are studied, Numerical results show the optimum transmitter elevation angle in a ka-band HAP-based communication system under fog attenuation.

Channel Attenuation Models over Ka Band Satellite Systems at Venezuelan Amazonian Area

2016 ◽  
Vol 841 ◽  
pp. 260-265
Author(s):  
Gustavo Guedez ◽  
Gao Qiang
Keyword(s):  
Low Frequency ◽  
Amazon Region ◽  
Atmospheric Gases ◽  
Ka Band ◽  
Satellite Systems ◽  
Clear Sky ◽  
Multipath Effects ◽  
Link Budget ◽  
Attenuation Models ◽  
Sky Conditions

The progressive congestion of the spectrum at low frequency bands, has obliged the need to use new systems which operate in higher frequencies, such as the Ka bands. The quality and availability of the signals in Ka band are seriously degraded by various climate phenomena, especially in the Amazon area. To keep the link properties in normal conditions (similar to clear sky conditions), is necessary to know the attenuation losses over the service area or footprint. For the Venezuelan Amazon region only Attenuation by atmospheric gases, Attenuation by rain and Scintillation and multipath effects, could be considered according to the ITU. The attenuation calculation is the first step to estimate the link budget and implement any communication service over Ka Band in the Venezuelan Amazon region. The aim of this research is modeling the channel attenuation for Ka band satellite signals and find a suitable attenuation data.

The Research on the Ka-Band Characteristics of the Satellite-Ground Link

2013 ◽  
Vol 336-338 ◽  
pp. 1726-1732
Author(s):  
Xin Li ◽  
Yue Ke Wang ◽  
Jian Yun Chen ◽  
Yong Bin Zhou
Keyword(s):  
Measurement System ◽  
Elevation Angle ◽  
Atmospheric Attenuation ◽  
Important Conclusion ◽  
Ka Band ◽  
Model Correction ◽  
Ground Measurement ◽  
Range Error

As the low-band is more and more crowded, moving to Ka-band for the satellite-ground measurement and communication is preferred in the literature. This paper aims to contribute to the understanding of the influence of the atmosphere on the range error and the attenuation in Ka-band. By adopting the method recommended by ITU-R, we analyze the delay range error and the attenuation induced by the ionosphere and troposphere for Ka-band. The result shows that the ionosphere delay range error is significantly reduced in Ka-band comparing with navigation band. The maximal ionosphere delay range error is about 1m in Ka-band. The troposphere delay range error in Ka-band is the same as that in navigation band. When the elevation angle is over 40º, the troposphere delay range error become flat and doesnt exceed approximately 4 m. With respect to atmospheric attenuation, two important findings are obtained: firstly, when the elevation angle is over 40º, the atmospheric attenuation doesnt change significantly and is generally below 2 dB. Secondly, the atmospheric attenuation reaches its peak at the frequency of approximately 22.5GHz in Ka-band. Finally, an important conclusion can be drawn that in the design of the Ka-band satellite-ground measurement system, it should be considered to make the system work at the elevation angle over 40º. Thus, in generally, the range error doesnt exceed 5 m and the attenuation doesnt exceed 2 dB, even though it doesnt make the model correction.

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