Design of GRACE-like Small Satellite Constellations for Improved Temporal Gravity Measurements.

2020 ◽  
Author(s):  
Carlos M.A. Deccia ◽  
David N. Wiese ◽  
Bryant D. Loomis ◽  
R. Steven Nerem
Keyword(s):  
Lower Cost ◽  
Single Point ◽  
Search Space ◽  
Population Based ◽  
Small Satellite ◽  
Satellite Constellations ◽  
Satellite Systems ◽  
Gravity Measurements ◽  
Temporal Gravity ◽  
Gravity Mission

<p>We have been investigating the science performance for different gravity mission constellation architectures using smallsats. Small satellite systems are increasingly being used in scientific missions, due to their increase in affordability and improvement in performance over the past years. A small satellite constellation of GRACE-like pairs or other inter satellite ranging configurations would allow for improved spatial and temporal resolution as well as allowing for a high inherent system redundancy and a lower overall cost. Additionally, such a mission architecture would be more robust to failure since a constellation is insensitive to single point failures and individual satellites can be replaced at a lower cost.<br />The design of such a mission architecture is not straightforward due to the vast search space that needs to be considered. In this work we make use of a multi-objective evolutionary algorithm that is population-based and metaheuristic based on Darwinian theory in order to identify future GRACE-like constellations that are optimized to retrieve sub-monthly time-varying gravity field events.</p>

Localization of WSN using Distributed Particle Swarm Optimization algorithm with precise references

2016 ◽  
Vol 7 ◽  
pp. 1
Author(s):  
Ravichander Janapati ◽  
Ch. Balaswamy ◽  
K. Soundararajan
Keyword(s):  
Particle Swarm Optimization ◽  
Search Algorithm ◽  
Particle Swarm ◽  
Search Space ◽  
Research Area ◽  
Population Based ◽  
Wireless Sensor ◽  
Cooperative Localization ◽  
Localization Algorithm ◽  
Swarm Optimization

Localization is the key research area in wireless sensor networks. Finding the exact position of the node is known as localization. Different algorithms have been proposed. Here we consider a cooperative localization algorithm with censoring schemes using Crammer Rao bound (CRB). This censoring scheme  can improve the positioning accuracy and reduces computation complexity, traffic and latency. Particle swarm optimization (PSO) is a population based search algorithm based on the swarm intelligence like social behavior of birds, bees or a school of fishes. To improve the algorithm efficiency and localization precision, this paper presents an objective function based on the normal distribution of ranging error and a method of obtaining the search space of particles. In this paper  Distributed localization of wireless sensor networksis proposed using PSO with best censoring technique using CRB. Proposed method shows better results in terms of position accuracy, latency and complexity.  

scholarly journals Forty-three years of absolute gravity observations of the Fennoscandian postglacial rebound in Finland

2021 ◽  
Vol 95 (2) ◽  
Author(s):  
Mirjam Bilker-Koivula ◽  
Jaakko Mäkinen ◽  
Hannu Ruotsalainen ◽  
Jyri Näränen ◽  
Timo Saari
Keyword(s):  
Gravity Data ◽  
Gravity Change ◽  
Global Navigation Satellite Systems ◽  
Absolute Gravity ◽  
Data Sets ◽  
Postglacial Rebound ◽  
Land Uplift ◽  
Satellite Systems ◽  
Gravity Measurements ◽  
Global Navigation Satellite

AbstractPostglacial rebound in Fennoscandia causes striking trends in gravity measurements of the area. We present time series of absolute gravity data collected between 1976 and 2019 on 12 stations in Finland with different types of instruments. First, we determine the trends at each station and analyse the effect of the instrument types. We estimate, for example, an offset of 6.8 μgal for the JILAg-5 instrument with respect to the FG5-type instruments. Applying the offsets in the trend analysis strengthens the trends being in good agreement with the NKG2016LU_gdot model of gravity change. Trends of seven stations were found robust and were used to analyse the stabilization of the trends in time and to determine the relationship between gravity change rates and land uplift rates as measured with global navigation satellite systems (GNSS) as well as from the NKG2016LU_abs land uplift model. Trends calculated from combined and offset-corrected measurements of JILAg-5- and FG5-type instruments stabilized in 15 to 20 years and at some stations even faster. The trends of FG5-type instrument data alone stabilized generally within 10 years. The ratio between gravity change rates and vertical rates from different data sets yields values between − 0.206 ± 0.017 and − 0.227 ± 0.024 µGal/mm and axis intercept values between 0.248 ± 0.089 and 0.335 ± 0.136 µGal/yr. These values are larger than previous estimates for Fennoscandia.

scholarly journals Blood Coagulation Algorithm: A Novel Bio-Inspired Meta-Heuristic Algorithm for Global Optimization

Mathematics ◽  
2021 ◽  
Vol 9 (23) ◽  
pp. 3011
Author(s):  
Drishti Yadav
Keyword(s):  
Blood Coagulation ◽  
Heuristic Algorithms ◽  
Cooperative Behavior ◽  
Real Life ◽  
Search Space ◽  
Population Based ◽  
Test Analysis ◽  
Search Spaces ◽  
Consistent Performance ◽  
The Comparative Study

This paper introduces a novel population-based bio-inspired meta-heuristic optimization algorithm, called Blood Coagulation Algorithm (BCA). BCA derives inspiration from the process of blood coagulation in the human body. The underlying concepts and ideas behind the proposed algorithm are the cooperative behavior of thrombocytes and their intelligent strategy of clot formation. These behaviors are modeled and utilized to underscore intensification and diversification in a given search space. A comparison with various state-of-the-art meta-heuristic algorithms over a test suite of 23 renowned benchmark functions reflects the efficiency of BCA. An extensive investigation is conducted to analyze the performance, convergence behavior and computational complexity of BCA. The comparative study and statistical test analysis demonstrate that BCA offers very competitive and statistically significant results compared to other eminent meta-heuristic algorithms. Experimental results also show the consistent performance of BCA in high dimensional search spaces. Furthermore, we demonstrate the applicability of BCA on real-world applications by solving several real-life engineering problems.

scholarly journals A Hybrid Computational Intelligence based Technique for Automatic Cryptanalysis of Playfair Ciphers

2020 ◽  
Vol 70 (6) ◽  
pp. 612-618
Author(s):  
Maiya Din ◽  
Saibal K. Pal ◽  
S. K. Muttoo ◽  
Sushila Madan
Keyword(s):  
Computational Intelligence ◽  
Text Message ◽  
Search Space ◽  
Population Based ◽  
English Text ◽  
Hybrid Technique ◽  
Brute Force ◽  
Symmetric Key ◽  
Brute Force Approach ◽  
Multiple Particle

The Playfair cipher is a symmetric key cryptosystem-based on encryption of digrams of letters. The cipher shows higher cryptanalytic complexity compared to mono-alphabetic cipher due to the use of 625 different letter-digrams in encryption instead of 26 letters from Roman alphabets. Population-based techniques like Genetic algorithm (GA) and Swarm intelligence (SI) are more suitable compared to the Brute force approach for cryptanalysis of cipher because of specific and unique structure of its Key Table. This work is an attempt to automate the process of cryptanalysis using hybrid computational intelligence. Multiple particle swarm optimization (MPSO) and GA-based hybrid technique (MPSO-GA) have been proposed and applied in solving Playfair ciphers. The authors have attempted to find the solution key applied in generating Playfair crypts by using the proposed hybrid technique to reduce the exhaustive search space. As per the computed results of the MPSO-GA technique, correct solution was obtained for the Playfair ciphers of 100 to 200 letters length. The proposed technique provided better results compared to either GA or PSO-based technique. Furthermore, the technique was also able to recover partial English text message for short Playfair ciphers of 80 to 120 characters length.

scholarly journals Hardware in the Loop Testing of Microsatellite Components

2021 ◽  
Author(s):  
Sarah Hardacre
Keyword(s):  
Kalman Filter ◽  
Hardware In The Loop ◽  
Small Satellite ◽  
Test Bed ◽  
Robust Controller ◽  
Satellite Systems ◽  
Helmholtz Coils ◽  
Space Agency ◽  
Satellite Sensors ◽  
And Control

The desire to bring space travel to a wider range of missions and uses has driven the market to using smaller and thus more affordable satellite systems. The Canadian Space Agency is completing the design and construction of a small satellite named QuickSat, which will utilize a magnetometer as one of its attitude and orbit determination instruments. A test bed comprised of three pairs of Helmholtz coils was used for hardware in the loop testing of the magnetometer. Testing was initially completed to prove the capabilities of the test bed, and then was completed to demonstrate the capabilities of the flight qualified magnetometer. The three pairs of Helmholtz coils were driven by data calculated from a spherical harmonic model of the Earth's magnetic field The coils were controlled using a robust controller and the magnetometer was used to drive the B-dot control law in the QuickSat simulation. The Ryerson Attitude and Control Experiment (RACE), which is a small satellite sized platform, free to spin about one axis on a near frictionless air bearing, was utilized to develop and test a system to deal with redundancy of satellite sensors. The possibility of missing, noisy or erroneous output during flight requires that a filter be applied to a satellite's flight code to determine with accuracy the attitude and orbit of the spacecraft. It was thus decided that a Kalman Filter be applied to RACE. The Kalman filter was applied to the RACE simulation successfully and initial hardware testing was carried out.

scholarly journals The Chromosome 9p21 CVD- and T2D-Associated Regions in a Norwegian Population (The HUNT2 Survey)

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Øyvind Helgeland ◽  
Jens K. Hertel ◽  
Anders Molven ◽  
Helge Ræder ◽  
Carl G. P. Platou ◽  
...  
Keyword(s):  
Single Point ◽  
Strong Association ◽  
Population Based ◽  
Risk Haplotype ◽  
Cross Sectional ◽  
Chromosome 9P21 ◽  
Snp Association ◽  
Risk Variants ◽  
Norwegian Population

Background.Two adjacent regions upstreamCDKN2Bon chromosome 9p21 have been associated with type 2 diabetes (T2D) and progression of cardiovascular disease (CVD). The precise location and number of risk variants have not been completely delineated and a possible synergistic relationship between the adjacent regions is not fully addressed. By a population based cross-sectional case-control design, we genotyped 18 SNPs upstream ofCDKN2Btagging 138 kb in and around two LD-blocks associated with CVD and T2D and investigated associations with T2D, angina pectoris (AP), myocardial infarction (MI), coronary heart disease (CHD; AP or AMI), and stroke using 5,564 subjects from HUNT2.Results.Single point and haplotype analysis showed evidence for only one common T2D risk haplotype (rs10757282∣rs10811661: OR = 1.19,P=2.0×10-3) in the region. We confirmed the strong association between SNPs in the 60 kb CVD region with AP, MI, and CHD(P<0.01). Conditioning on the lead SNPs in the region, we observed two suggestive independent single SNP association signals for MI,rs2065501  (P=0.03)andrs3217986  (P=0.04).Conclusions.We confirmed the association of known variants within the 9p21 interval with T2D and CHD. Our results further suggest that additional CHD susceptibility variants exist in this region.

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