scholarly journals Experimental Research on Narrowband Interference Suppression of GNSS Signals

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Bin Wang ◽  
Yanjing Sun ◽  
Yang Liu ◽  
Yuzhi Zhang ◽  
Song Li
Keyword(s):  
Experimental Research ◽  
Urban Environments ◽  
Lms Algorithm ◽  
Signal System ◽  
Signal Power ◽  
Narrowband Interference ◽  
Test Environment ◽  
Contrast Analysis ◽  
Set Up ◽  
Actual Test

The navigation satellites are running at a high altitude of 20000 km from the ground, and the satellite signals arriving at the ground are very weak, such as the C/A code on the L1 band, which is only -160 dBW. In complex urban environments, especially when there is an occlusion, the signal power will be even lower. Low power causes the signal to be easily disturbed, where suppressed interference is the most common method of interference. The purpose of this paper is to experiment with the BPSK and BOC signal system to do the narrowband suppression of interference analysis and set up the actual test environment, based on the commonly used LMS algorithm for the two systems of narrowband interference performance contrast analysis, and throughout the simulation, it can be seen that the two improved algorithms can effectively suppress narrowband interference, thus improving the anti-interference performance of satellite navigation receiver.

scholarly journals Sound Localization Test in Presence of Noise (Sound Localization Test) in Adults without Hearing Alteration

2019 ◽  
Vol 23 (03) ◽  
pp. e276-e280
Author(s):  
Gleide Viviani Maciel Almeida ◽  
Angela Ribas ◽  
Jorge Calleros
Keyword(s):  
Sound Localization ◽  
Free Field ◽  
Normal Hearing ◽  
Average Score ◽  
Test Environment ◽  
Noise Interference ◽  
Localization Test ◽  
The Subject ◽  
Set Up ◽  
The Right

Introduction Even people with normal hearing may have difficulties locating a sound source in unfavorable sound environments where competitive noise is intense. Objective To develop, describe, validate and establish the normality curve of the sound localization test. Method The sample consisted of 100 healthy subjects with normal hearing, > 18 years old, who agreed to participate in the study. The sound localization test was applied after the subjects underwent a tonal audiometry exam. For this purpose, a calibrated free field test environment was set up. Then, 30 random pure tones were presented in 2 speakers placed at 45° (on the right and on the left sides of the subject), and the noise was presented from a 3rd speaker, placed at 180°. The noise was presented in 3 hearing situations: optimal listening condition (no noise), noise in relation to 0 dB, and noise in relation to - 10 dB. The subject was asked to point out the side where the pure tone was being perceived, even in the presence of noise. Results All of the 100 participants performed the test in an average time of 99 seconds. The average score was 21, the medium score was 23, and the standard deviation was 3.05. Conclusion The sound localization test proved to be easy to set-up and to apply. The results obtained in the validation of the test suggest that individuals with normal hearing should locate 70% of the presented stimuli. The test can constitute an important instrument in the measurement of noise interference in the ability to locate the sound.

Geometric Deformations of Welded Metallic Structures

2014 ◽  
Vol 657 ◽  
pp. 342-347 ◽  
Author(s):  
Andreea Mădălina Ene Căscătău ◽  
Patrice Plassais ◽  
Marian Gheorghe
Keyword(s):  
Experimental Research ◽  
Process Parameters ◽  
Measurement System ◽  
Quality Characteristics ◽  
Welding Robot ◽  
Metallic Structure ◽  
Metallic Structures ◽  
Welded Structure ◽  
Geometric Deformation ◽  
Set Up

Various research on the influence of different process parameters on quality characteristics of metallic structures assembled by welding have been accomplished [1 - 8, etc.]. The deformations of metallic structure components assembled by welding depend on the characteristics of the components, welded gap, welding speed, scheme and time of components fixing, etc. The paper presents the data and main results of an experimental research on the influence of two process parameters - the welding gap and the fixing time of the components - on the geometric deformations of certain metallic structure components in industrial conditions. Complex experiment and set-up including industrial welding robot and advanced measurement system have been designed and used. The geometric deformations of the welded metallic structure components are caused by forces and phenomenon heating - cooling, i.e. dilatation - contraction, respectively, acting during the periods of fixing - welding, fixing - cooling, cooling without fixing. Relevant dependences between the geometric deformation of welded structure and the considered influencing process parameters have been evidenced.

scholarly journals Research on the Monocular Ranging Method of the Leading Vehicle in Multi-weather

2021 ◽  
pp. 61-72
Author(s):  
Yong Tian ◽  
Quancai Li ◽  
Shuman Guo ◽  
Gongrou Fu ◽  
Shichang Wang ◽  
...  
Keyword(s):  
Measurement Method ◽  
Weather Conditions ◽  
Distance Measurement ◽  
Test Environment ◽  
Set Up ◽  
Ranging Errors ◽  
Fitted Function ◽  
Pixel Mapping ◽  
Longitudinal Distance ◽  
Ranging Model

In order to improve the accuracy of the monocular distance measurement of the vehicle in front under sunny, cloudy, rainy, snowy, and foggy weather, an improved pixel-mapping monocular distance measurement method is proposed. This method is based on eight-connected domains to detect the front vehicle, obtain the line pixels of the target vehicle in the image, and fit the image line pixels to the corresponding real longitudinal distance function, and combine the fitted function with the internal and external parameters of the camera. An improved pixel-mapping monocular ranging model is obtained. Set up a test environment under different weather to verify the feasibility of the algorithm. The results show that in the four environments, the detectable distances are within 70m, 60m, 30m, and 40m respectively; the error of the improved pixel-mapping monocular ranging method is reduced by 0.6% on average compared with before the improvement, up to 0.92% ; The improved algorithm ranging errors under the four weathers are 1.8513%, 2.6987%, 4.0137%, and 2.5795% respectively, which achieves the purpose of improving the accuracy of the monocular distance measurement of the vehicle in front under multiple weather conditions.

scholarly journals High Resolution Air Quality Forecasting over Prague within the URBI PRAGENSI Project: Model Performance during the Winter Period and the Effect of Urban Parameterization on PM

Atmosphere ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 625 ◽  
Author(s):  
Jana Ďoubalová ◽  
Peter Huszár ◽  
Kryštof Eben ◽  
Nina Benešová ◽  
Michal Belda ◽  
...  
Keyword(s):  
Air Quality ◽  
Model Performance ◽  
Urban Canopy ◽  
Urban Environments ◽  
Winter Period ◽  
Air Quality Model ◽  
Quality Model ◽  
Boundary Layer Height ◽  
Project Model ◽  
Set Up

The overall impact of urban environments on the atmosphere is the result of many different nonlinear processes, and their reproduction requires complex modeling approaches. The parameterization of these processes in the models can have large impacts on the model outputs. In this study, the evaluation of a WRF/Comprehensive Air Quality Model with Extensions (CAMx) forecast modeling system set up for Prague, the Czech Republic, within the project URBI PRAGENSI is presented. To assess the impacts of urban parameterization in WRF, in this case with the BEP+BEM (Building Environment Parameterization linked to Building Energy Model) urban canopy scheme, on Particulate Matter (PM) simulations, a simulation was performed for a winter pollution episode and compared to a non-urbanized run with BULK treatment. The urbanized scheme led to an average increase in temperature at 2 m by 2 ∘ C, a decrease in wind speed by 0.5 m s − 1 , a decrease in relative humidity by 5%, and an increase in planetary boundary layer height by 100 m. Based on the evaluation against observations, the overall model error was reduced. These impacts were propagated to the modeled PM concentrations, reducing them on average by 15–30 μ g m − 3 and 10–15 μ g m − 3 for PM 10 and PM 2.5 , respectively. In general, the urban parameterization led to a larger underestimation of the PM values, but yielded a better representation of the diurnal variations.

scholarly journals Optimising Test Environment and Test Set Up for Characterizing Actual Thermal Performance of Building Components and Whole Buildings

2015 ◽  
Vol 78 ◽  
pp. 3264-3269 ◽  
Author(s):  
M. Fletcher ◽  
A. Erkoreka ◽  
C. Gorse ◽  
K. Martin ◽  
J.M. Sala
Keyword(s):  
Thermal Performance ◽  
Test Environment ◽  
Test Set ◽  
Building Components ◽  
Set Up

Experimental Research of Rebound Detection in Steel Fiber Concrete

2014 ◽  
Vol 578-579 ◽  
pp. 1108-1112 ◽  
Author(s):  
Jian Feng Ye ◽  
Hua Yan Chen ◽  
Xian Shun Bi
Keyword(s):  
Regression Analysis ◽  
Fly Ash ◽  
Experimental Research ◽  
Compression Strength ◽  
Steel Fiber ◽  
Detection Method ◽  
Fiber Concrete ◽  
Testing Data ◽  
Steel Fiber Concrete ◽  
Set Up

For the application into country point highway of Xiamen to Kunming, a series of the C40 concrete with fly ash and slag have been studied by rebound detection and compression strength, the detecting wave of rebound value and compression strength is set up by regression analysis of the testing data. It is shown from the example that the compression strength and rebound value have good relativity, this rebound detection method used in steel fiber concrete is simple and practical.

Experimental Research on Brittle Shale Failure Caused by Drilling Fluid Activity

2013 ◽  
Vol 807-809 ◽  
pp. 2550-2553 ◽  
Author(s):  
Ming Wang Peng ◽  
Hang Wen ◽  
Wei Zhou ◽  
Zhao Jun Wen ◽  
Xiao Ming Liu ◽  
...  
Keyword(s):  
Internal Structure ◽  
Experimental Research ◽  
Rock Strength ◽  
Drilling Fluid ◽  
Expansion Ratio ◽  
Wellbore Stability ◽  
Test Results ◽  
Fracture Formation ◽  
Set Up ◽  
Activity Window

The crack formed under the action of circular medium fluid around the wellbore of brittle shale has been a hot issue in recent years. This paper considers the brittle shale micro fracture formation mechanism from the perspective of inhibitive ability of drilling fluid activity. The model of activity-swelling-hydration is set up firstly through revising generalized Usher model, it states the drilling fluid activity range to keep wellbore in osmotic hydration stage with the critical expansion ratio, thus puts forward the concept of activity window and is verified by indoor test. Results show that the different activity of drilling fluid brings difference in rock strength in macro and time sensitive effect for internal structure of rock in micro. This mechanism can provide a more accurate range design for drilling fluid activity and strong guarantee for wellbore stability.

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