scholarly journals An Analytical Prediction Model of Time Diversity Performance for Earth-Space Fade Mitigation

2008 ◽  
Vol 2008 ◽  
pp. 1-5 ◽  
Author(s):  
Pantelis-Daniel M. Arapoglou ◽  
Athanasios D. Panagopoulos ◽  
Panayotis G. Cottis
Keyword(s):  
Prediction Model ◽  
High Frequency ◽  
Rain Attenuation ◽  
Analytical Prediction ◽  
Time Dynamics ◽  
Time Diversity ◽  
Satellite Applications ◽  
Basic Parameters ◽  
Cost Efficient ◽  
General Prediction

Time diversity (TD) has recently attracted attention as a promising and cost-efficient solution for high-frequency broadcast satellite applications. The present work proposes a general prediction model for the application of TD by approximating the time dynamics of rain attenuation through the use of the joint lognormal distribution. The proposed method is tested against experimental data and its performance is investigated with respect to the basic parameters of a satellite link.

scholarly journals A Systemic Approach to the Compensation of Rain Attenuation in Ka-Band Communication Satellites

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Piero Angeletti ◽  
Marco Lisi
Keyword(s):  
Satellite Communications ◽  
Integrated Approach ◽  
Rain Attenuation ◽  
Systemic Approach ◽  
Band Spectrum ◽  
Effective Solution ◽  
Combined Approach ◽  
Adaptive Compensation ◽  
Ka Band ◽  
Satellite Applications

Rain attenuation at Ka-band is a severe phenomenon that drastically impairs satellite communications at these frequencies. Several adaptive compensation techniques have been elaborated to counteract its effects and most often applied one at a time. The present paper proposes the contemporary exploitation of different techniques in a combined approach. Such an integrated approach is thoroughly analyzed in a simplified scenario and will be shown to achieve a very effective solution, making the Ka-band spectrum fully available for broadband satellite applications and network-centric systems.

Validation of New ITU-R Rain Attenuation Prediction Model over Malaysia Equatorial Region

MAPAN ◽  
2018 ◽  
Vol 34 (1) ◽  
pp. 71-77 ◽  
Author(s):  
F. A. Semire ◽  
R. Mohd-Mokhtar ◽  
I. A. Akanbi
Keyword(s):  
Prediction Model ◽  
Rain Attenuation ◽  
Equatorial Region

scholarly journals Analysis of rain fade slope for terrestrial links

2020 ◽  
Vol 18 (2) ◽  
pp. 896
Author(s):  
Jalel Chebil ◽  
Al-Hareth Zyoud ◽  
Mohamed Hadi Habaebi ◽  
Islam Md. Rafiqul ◽  
Hassan Dao
Keyword(s):  
Standard Deviation ◽  
Prediction Model ◽  
Rain Attenuation ◽  
Measured Data ◽  
Rate Of Change ◽  
Tropical Regions

<p><span>Rainfall can cause severe degradation to the operation of microwave links working with frequencies above 10 GHz. Many studies have investigated this problem, and one of the factors that attract the attention of researcher is rain fade slope which is the rate of change of rain attenuation.</span><span> The focus of this study is on rain fade slope for terrestrial links and it is </span><span>based on measurement conducted in Malaysia</span><span>.</span><span> This paper investigates the characteristics of the measured rain fade slope distribution </span><span>for various attenuation levels</span><span>. Then, </span><span>the ITU-R model for rain fade slope is compared with the corresponding statistics obtained from the measured data. Significant discrepancies have been observed since the ITU-R prediction model does not fit the measured fade slope distribution for many attenuation levels. It is recommended to modify the expression of the standard deviation in the ITU-R model when implemented in tropical regions.</span></p>

scholarly journals Analysis of Time Diversity Gain for Satellite Communication Link based on Ku-Band Rain Attenuation Data Measured in Malaysia

2018 ◽  
Vol 8 (4) ◽  
pp. 2608
Author(s):  
Islam Md. Rafiqul ◽  
Ali Kadhim Lwas ◽  
Mohamed Hadi Habaebi ◽  
Md Moktarul Alam ◽  
Jalel Chebil ◽  
...  
Keyword(s):  
Satellite Communication ◽  
Satellite Communications ◽  
Earth Satellite ◽  
Rain Attenuation ◽  
Diversity Gain ◽  
Communication Link ◽  
Time Diversity ◽  
Communication Links ◽  
System Time ◽  
Diversity Technique

<p><span>This paper reports a study on mitigation of propagation impairments on Earth–space communication links. The study uses time diversity as a technique for mitigating rain propagation impairment in order to rectify rain fade. Rain attenuation time series along earth-to-satellite link were measured for two years period at 12.255 GHz in Malaysia. The time diversity technique was applied on measured rain fade to investigate the level of possible improvement in system. Time diversity gain from measured one-minute rain attenuation for two years period was estimated and significant improvement was observed with different delays of time. These findings will be utilized as a useful tool for link designers to apply time diversity as a rain fade mitigation technique in Earth-satellite communications systems.</span></p>

Aerosol Printing of High Resolution Films for LTCC-Multilayer Components

2012 ◽  
Vol 9 (3) ◽  
pp. 133-137 ◽  
Author(s):  
Martin Ihle ◽  
Uwe Partsch ◽  
Sindy Mosch ◽  
Adrian Goldberg
Keyword(s):  
High Resolution ◽  
High Frequency ◽  
High Reliability ◽  
Direct Write ◽  
Printing Technology ◽  
Fine Line ◽  
Aerosol Printing ◽  
Fine Structures ◽  
Cost Efficient ◽  
Printing Parameters

For the electronic packaging of sensor stable and cost-efficient fine line printing technologies on LTCC and high frequency laminates are needed. Especially common technologies like screen printing and thin film techniques are unsuitable for fine structures or too expensive. In addition, there is no direct write technology for 3D LTCC designs as well as for high reliability cofiring structures. Closing this gap, aerosol printing technology is used to print high resolution conductors on planar and nonplanar substrates. Aerosol printing is a direct write noncontact printing technology of functional layers. After pneumatic atomization, the ink is transformed into 1–5 μm droplets. The resulting continuous aerosol stream is focused by a sheath gas in the printing head. Thus, the long standoff distance between the substrate and the deposition tip of max. 5 mm allows 3D printing on nonplanar substrates. With optimized inks and printing parameters, line widths of 10 μm are achievable. This paper will present applications for aerosol printed functional layers on LTCC. These are, for example, aerosol printed films embedded in cofired LTCC, fine line structures for high frequency applications, and the evaluation of printed 3D structures like LTCC stairways. Furthermore, the 90° contact of unconventional sensor designs will be presented.

scholarly journals A Vibration-Isolated Body of Chaotic Prediction

2011 ◽  
Vol 2-3 ◽  
pp. 978-983
Author(s):  
Yong Yi Gao ◽  
Shi Ping Zhan ◽  
Ban Gyan Li
Keyword(s):  
High Frequency ◽  
Simulation Experiment ◽  
Variable Parameter ◽  
Slow Variable ◽  
State Equation ◽  
Analytical Prediction ◽  
Vibration Isolator ◽  
Weak Nonlinearity ◽  
Analog Simulation ◽  
Inherent Frequency

The nonlinear dynamics equation of passive vibration isolator is established in this paper. According to the nonlinear vibration theory, the average equation of slow-varying primary harmonic in the condition of weak nonlinearity is abstained , and derived a discrete mapping of the harmonic slow variable parameter state equation, then get the analytical conditions of chaos in the passive vibration isolator, the analytical results show that only when the vibration frequency of the groundsill is higher than the inherent frequency of the passive vibration isolator, the chaos can be observed, when the groundsill vibrate with the large amplitude and high frequency vibration, the chaos can’t be observed in the passive vibration isolator system. Finally the analytical prediction is validated by analog simulation experiment, and gets the conclusion that the prediction matches well with the simulation results.

Analytical Prediction and Experimental Investigation of Burnishing Force in Rotary Ultrasonic Roller Burnishing Titanium Alloy Ti–6Al–4V

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Jian Zhao ◽  
Zhanqiang Liu ◽  
Bing Wang ◽  
Yukui Cai ◽  
Qinghua Song
Keyword(s):  
Titanium Alloy ◽  
Prediction Model ◽  
Milling Process ◽  
Analytical Prediction ◽  
Ultrasonic Power ◽  
Machined Surface ◽  
Softening Effect ◽  
Force Prediction ◽  
Contact Width ◽  
Acoustic Softening

Abstract Ultrasonic burnishing is usually applied to make machined surface modification. The acoustic softening effect caused by ultrasonic vibration is beneficial to the machining of difficult-to-cut materials. In the present work, a burnishing force prediction model was proposed for rotary ultrasonic burnishing of titanium alloy Ti–6Al–4V, whose surface had been machined with the face milling process. Firstly, the contact between the burnishing roller and one single milling mark was analyzed with plane strain assumption based on the Boussinesq–Flamant contact problem. Then, the effect of ultrasonic softening on the yield stress of Ti–6Al–4V was investigated. The critical contact width and contact load that the burnishing roller crushed on one single milling mark were examined to confirm the feasibility of the proposed ultrasonic burnishing force prediction model. The experimental verifications were carried out at various ultrasonic powers. The burnishing forces from experiment measurements were consistent with the calculated results from the proposed model. The mean deviations between theoretical and experimental results of the ultrasonic burnishing force were 10.4%, 12.2%, and 15.2%, corresponding to the ultrasonic power at the level of 41 W, 158 W, and 354 W, respectively.

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