scholarly journals Performance in Solar Orientation Determination for Regular Pyramid Sun Sensors

Sensors ◽  
2019 ◽  
Vol 19 (6) ◽  
pp. 1424 ◽  
Author(s):  
Jiang Wang ◽  
Yongchao Zhang ◽  
Yin Zhang ◽  
Yulin Huang ◽  
Jianyu Yang ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Field Experiments ◽  
Detection System ◽  
Elevation Angle ◽  
Limiting Factor ◽  
Frequency Domain Method ◽  
Solar Panels ◽  
Method Error ◽  
Solar Orientation ◽  
Orientation Determination

Non-planar sun sensors can determine solar orientation by existing photodiodes or by reusing solar panels, without increasing the size and mass of spacecraft. However, a limiting factor for the improvement of the accuracy of orientation lies in the lack of a detailed performance assessment on interference suppression. In this paper, a new method that determines solar orientation in the frequency domain is developed for regular pyramid sun sensors, which are formed by regular pyramid arrays. Furthermore, two formulations are established to evaluate the errors of the solar azimuth and elevation angle in solar orientation determination based on the newly proposed frequency-domain method. With these formulations of performance evaluation, we discover the mathematical relationship between the interference spectrum, array geometry, solar irradiance, solar azimuth or elevation angle, and the error in solar orientation determination for the first time. This reveals that the internal interference from the detection system can be completely suppressed in solar orientation determination, and the constant interference can be eliminated in the estimation of solar azimuth angle. Simulation and field experiments validated the effectiveness of the new orientation method, error formulations and performance of each interference source.

A Solar Power Storage Trolley

2013 ◽  
Vol 291-294 ◽  
pp. 168-171
Author(s):  
Jian Feng Wu ◽  
Jian Qing Li ◽  
Le Gu ◽  
Lei Wang ◽  
Li Bo Zhang
Keyword(s):  
Solar Energy ◽  
Light Intensity ◽  
Elevation Angle ◽  
Azimuth Angle ◽  
The Sun ◽  
Solar Panels ◽  
Test Experiment ◽  
Orientation Sensor ◽  
Power Storage ◽  
Solar Orientation

In order to improve the accumulating efficiency of solar energy, we designed a trolley with a 2-DOF attitude regulation structure of solar panels. In it, a solar orientation sensor was used to detect the solar orientation and the solar light intensity. A trolley’s differential wheels and a steering engine were used to keep the solar panels of the trolley vertically facing the Sun. At a certain interval, the steering engine adjusted the elevation angle of the solar panels and the trolley’s differential wheels adjusted the solar panels’ azimuth angle. Test experiment results show that the trolley can improve the accumulating efficiency of solar energy.

Proposed Hybrid Classifier to Improve Network Intrusion Detection System using Data Mining Techniques

2020 ◽  
Vol 38 (1B) ◽  
pp. 6-14
Author(s):  
ٍٍSarah M. Shareef ◽  
Soukaena H. Hashim
Keyword(s):  
Intrusion Detection ◽  
False Alarm ◽  
Intrusion Detection System ◽  
Detection System ◽  
Multinomial Logistic Regression ◽  
Network Intrusion Detection ◽  
Limiting Factor ◽  
Network Intrusion ◽  
Network Intrusion Detection System ◽  
Normal Behavior

Network intrusion detection system (NIDS) is a software system which plays an important role to protect network system and can be used to monitor network activities to detect different kinds of attacks from normal behavior in network traffics. A false alarm is one of the most identified problems in relation to the intrusion detection system which can be a limiting factor for the performance and accuracy of the intrusion detection system. The proposed system involves mining techniques at two sequential levels, which are: at the first level Naïve Bayes algorithm is used to detect abnormal activity from normal behavior. The second level is the multinomial logistic regression algorithm of which is used to classify abnormal activity into main four attack types in addition to a normal class. To evaluate the proposed system, the KDDCUP99 dataset of the intrusion detection system was used and K-fold cross-validation was performed. The experimental results show that the performance of the proposed system is improved with less false alarm rate.

scholarly journals Velocity model building by 3D frequency-domain, full-waveform inversion of wide-aperture seismic data

Geophysics ◽  
2008 ◽  
Vol 73 (5) ◽  
pp. VE101-VE117 ◽  
Author(s):  
Hafedh Ben-Hadj-Ali ◽  
Stéphane Operto ◽  
Jean Virieux
Keyword(s):  
High Resolution ◽  
Frequency Domain ◽  
Distributed Memory ◽  
Waveform Inversion ◽  
Steepest Descent Method ◽  
Frequency Domain Method ◽  
Full Waveform Inversion ◽  
Direct Solver ◽  
Velocity Models ◽  
Full Waveform

We assessed 3D frequency-domain (FD) acoustic full-waveform inversion (FWI) data as a tool to develop high-resolution velocity models from low-frequency global-offset data. The inverse problem was posed as a classic least-squares optimization problem solved with a steepest-descent method. Inversion was applied to a few discrete frequencies, allowing management of a limited subset of the 3D data volume. The forward problem was solved with a finite-difference frequency-domain method based on a massively parallel direct solver, allowing efficient multiple-shot simulations. The inversion code was fully parallelized for distributed-memory platforms, taking advantage of a domain decomposition of the modeled wavefields performed by the direct solver. After validation on simple synthetic tests, FWI was applied to two targets (channel and thrust system) of the 3D SEG/EAGE overthrust model, corresponding to 3D domains of [Formula: see text] and [Formula: see text], respectively. The maximum inverted frequencies are 15 and [Formula: see text] for the two applications. A maximum of 30 dual-core biprocessor nodes with [Formula: see text] of shared memory per node were used for the second target. The main structures were imaged successfully at a resolution scale consistent with the inverted frequencies. Our study confirms the feasibility of 3D frequency-domain FWI of global-offset data on large distributed-memory platforms to develop high-resolution velocity models. These high-velocity models may provide accurate macromodels for wave-equation prestack depth migration.

Leak detection in pipelines by exclusively frequency domain method

2012 ◽  
Vol 55 (3) ◽  
pp. 743-752 ◽  
Author(s):  
XinLei Guo ◽  
KaiLin Yang ◽  
YongXin Guo
Keyword(s):  
Frequency Domain ◽  
Leak Detection ◽  
Frequency Domain Method ◽  
Domain Method
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