RESUMEN
In the complex and variable marine environment, the navigation and localization of autonomous underwater vehicles (AUVs) are very important and challenging. When the conventional Kalman filter (KF) is applied to the cooperative localization of leader-follower AUVs, the outliers in the sensor observations will have a substantial adverse effect on the localization accuracy of the AUVs. Meanwhile, inaccurate noise covariance matrices may result in significant estimation errors. In this paper, we proposed an improved Sage-Husa adaptive extended Kalman filter (improved SHAEKF) for the cooperative localization of multi-AUVs. Firstly, the measurement anomalies were evaluated by calculating the Chi-square test statistics based on the innovation. The detection threshold was determined according to the confidence level of the Chi-square test, and the Chi-square test statistics exceeding the threshold were regarded as measurement abnormalities. When measurement anomalies occurred, the Sage-Husa adaptive extended Kalman filter algorithm was improved by suboptimal maximum a posterior estimation using weighted exponential fading memory, and the measurement noise covariance matrix was adjusted online. The numerical simulation of leader-follower multi-AUV cooperative localization verified the effectiveness of the improved SHAEKF and demonstrated that the average root mean square and the average standard deviation of the localization errors based on the improved SHAEKF were significantly reduced in the case of the presence of measurement abnormalities.
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Algoritmos , Proyectos de Investigación , Simulación por ComputadorRESUMEN
We demonstrated experimental comparison between ghost imaging and traditional non-correlated imaging under disturbance of scattering. Ghost imaging appears more robust. The quality of ghost imaging does not change much when the scattering is getting stronger, while that of traditional imaging declines dramatically. A concise model is developed to explain the superiority of ghost imaging. Due to its robustness against scattering, ghost imaging will be useful in harsh environment.
RESUMEN
Columnar apple is an important genetic resource for tree form breeding of apple. In this study, 106 individuals of the F1 population derived from 'Spur Fuji' (coco)x 'Telamon'(Coco) were used as plant materials for screening SSR markers linked to gene. By bulked segregating analysis (BSA), eight SSR markers from the tenth linkage group of apple genome were tested. Finally, three of them, COL, CH02a10 and CH03d11, were identified to be SSR markers of Co gene. Linkage analysis showed that the genetic distance of COL, CH02a10 and CH03d11 to Co locus was 15.3cM, 22.2cM and 3.9 cM, respectively. On the linkage map of these markers, Co gene was located between COL and CH03d11.
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Malus/genética , Repeticiones de Minisatélite/genética , Proteínas de Plantas/genética , Ligamiento Genético/genéticaRESUMEN
A DNA marker linked to the columnar gene (Co) in apple (Malus domestica) was explored based on the population of 105 progenies of 'Spur Fuji' x 'Telamon' by bulk segregant analysis (BSA) and Random Amplified Polymorphic DNA (RAPD) technique. A total of 300 random primers were screened and a RAPD marker (S1142(682)) closely linked to Co gene (2.86 cM) was identified and then sequenced. Four specific PCR primers (two forward primers and two reverse primers) were designed,and the products of SCAR-PCR indicated that all the four pairs of primers could amplify polymorphic bands between columnar and non-columnar traits, so any of them could serve as the specific SCAR primers. One pair of these specific primers was chosen to amplify each individual in the population, and the result showed that the co-segregation pattern of this SCAR marker and Co gene was the same as that of the RAPD marker. Furthermore, it was found that the nucleotide sequence of the RAPD marker fragment contained an open reading frame (ORF) that could encode 68 deduced amino acid residues at the position of +45 - +251.