60 research outputs found

    Electron Density Reconstruction of Solar Coronal Mass Ejections Based on a Genetic Algorithm: Method and Application

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    We present a new method to reconstruct the three-dimensional electron density of coronal mass ejections (CMEs) based on a genetic algorithm, namely the genetic reconstruction method (GRM). GRM is first applied to model CMEs with different orientations and shapes. A set of analytic model CMEs from Gibson and Low is employed to produce synthetic CME images for GRM reconstruction. Model CMEs with longitudes of 0, 45, 90, 135, 180 degrees and latitudes of 0, 15, 30, 45 degrees are used to test the performance of GRM. The model CMEs are obscured with a simulated occulter of a coronagraph to determine the influence of CME brightness incompleteness. We add random noise to some synthetic CME images to test the performance of GRM. The CME reconstructions are carried out using synthetic data from Solar Terrestrial Relations Observatory (STEREO) A and B with a separation angle of 90 degrees and from STEREO A and the Solar and Heliospheric Observatory (SOHO) with a separation angle of 73 degrees. The Pearson correlation coefficient and the mean relative absolute deviation are calculated to analyze the similarities in brightness and electron density between the model and reconstructed CMEs. Comparisons based on the similarity analysis under various conditions stated above give us valuable insights into the advantages and limitations of GRM reconstruction. The method is then applied to real coronagraph data from STEREO A and B, and SOHO on 2013 September 30.Comment: 27 pages, 17 figures, 1 table. Published on Ap

    Intelligent Control and Parameter Calculation of Highway Truck Escape Ramp

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    To reduce the probability of secondary accidents caused by the direction deviation, body rollover, and excessive deceleration of runaway vehicles during braking on a truck escape ramp (TER), the safety of the occupants and the vehicles must be ensured. Based on the momentum theorem, an intelligent control method for a TER is proposed. In the method, a slope aggregate with a small rolling resistance coefficient is used on the original escape lane, and the information acquisition, braking device control, and braking modules are established. Through these modules, the operation parameters and control parameters of the out-of-control vehicle are obtained in advance, to control the operation state of the runaway vehicle. Achieve the purpose of reducing the braking effect of the slope bed aggregate and ensuring maximum utilization of the braking ramp. Finally, the proposed control method is simulated on the MATLAB/Simulink simulation platform. The results show that the control method can realize safe braking of an out-of-control vehicle at various speeds and different mass conditions, and it can play a highly significant role in the braking of high-speed and heavy-duty vehicles

    Highly time-resolved chemical characterization and implications of regional transport for submicron aerosols in the North China Plain

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    To investigate the regional transport and formation mechanisms of submicron aerosols in the North China Plan (NCP), for the first time, we conducted simultaneous combined observations of the non-refractory submicron aerosols (NR-PM1) chemical compositions using aerosol mass spectrometer at urban Beijing (BJ) and at regional background area of the NCP (XL), from November 2018 to January 2019. During the observation period, average mass concentrations of PM1 in BJ and XL were 26.6 +/- 31.7 and 16.0 +/- 18.7 mu g m(-3) respectively. The aerosol composition in XL showed a lower contribution of organic aerosol (33% vs. 43%) and higher fractions of nitrate (35% vs. 30%), ammonium (16% vs. 13%), and chlorine (2% vs. 1%) than in BJ. Additionally, a higher contribution of secondary organic aerosol (SOA) was also observed in XL, suggesting low primary emissions and highly oxidized OA in the background area. Nitrate displayed a significantly enhanced contribution with the aggravation of aerosol pollution in both BJ and XL, which was completely neutralized by excess ammonium at both sites, that the abundant ammonia emissions in the NCP favor nitrate formation on a regional scale. In addition, a higher proportion of nitrate in XL can be attributed to the more neutral and higher oxidation capacity of the background atmosphere. Heterogeneous aqueous reaction plays an important role in sulfate and SOA formation, and is more efficient in BJ which can be attributed to the higher aerosol surface areas at urban site. Regional transport from the southwestern regions of NCP showed a significant impact on the formation of haze episodes. Beside the invasion of transported pollutants, the abundant water vapor associated with the air mass to the downwind background area further enhanced local secondary transformation and expanded the regional scope of the haze pollution in the NCP. (C) 2019 Elsevier B.V. All rights reserved.Peer reviewe

    Analysis of Large Phenotypic Variability of EEC and SHFM4 Syndromes Caused by K193E Mutation of the TP63 Gene

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    EEC (ectrodactyly, ectodermal dysplasia, clefting; OMIM 604292) is an autosomal dominant developmental disorder resulting mainly from pathogenic mutations of the DNA-binding domain (DBD) of the TP63 gene. In this study, we showed that K193E mutation in nine affected individuals of a four-generation kindred with a large degree of phenotypic variability causes four different syndromes or TP63-related disorders: EEC, Ectrodactyly-ectodermal dysplasia (EE), isolated ectodermal dysplasia, and isolated Split Hand/Foot Malformation type 4 (SHFM4). Genotype-phenotype and DBD structural modeling analysis showed that the K193-located loop L2-A is associated with R280 through hydrogen bonding interactions, while R280 mutations also often cause large phenotypic variability of EEC and SHFM4. Thus, we speculate that K193 and several other DBD mutation-associated syndromes may share similar pathogenic mechanisms, particularly in the case of the same mutation with different phenotypes. Our study and others also suggest that the phenotypic variability of EEC is attributed, at least partially, to genetic and/or epigenetic modifiers

    Research on Stereo Vision Technology Based on Improved Region Growing Method

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    Abstract Image segmentation is the cornerstone of image analysis and image processing, its main difficulty is the ill-posedness of image segmentation. The region growing method is the most commonly used method in image segmentation. Its advantages are fast calculation speed, lower algorithm difficulty, and easy understanding. This article uses the area growing algorithm and TOF combined with binocular fusion technology. Discussed how to select the seed points in the region growing method. The algorithm proposed in this paper has high accuracy and high matching quality in the boundary area of the object and the area with large difference in depth. It has both matching time and reliability. It has good results and overcomes the limitations of the active and passive distance methods in the vision system

    Sum Rate Optimization of Multi-Standard IEEE 802.11 WLANs

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    Bilinear CNN Model for Fine-Grained Classification Based on Subcategory-Similarity Measurement

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    One of the challenges in fine-grained classification is that subcategories with significant similarity are hard to be distinguished due to the equal treatment of all subcategories in existing algorithms. In order to solve this problem, a fine-grained image classification method by combining a bilinear convolutional neural network (B-CNN) and the measurement of subcategory similarities is proposed. Firstly, an improved weakly supervised localization method is designed to obtain the bounding box of the main object, which allows the model to eliminate the influence of background noise and obtain more accurate features. Then, sample features in the training set are computed by B-CNN so that the fuzzing similarity matrix for measuring interclass similarities can be obtained. To further improve classification accuracy, the loss function is designed by weighting triplet loss and softmax loss. Extensive experiments implemented on two benchmarks datasets, Stanford Cars-196 and Caltech-UCSD Birds-200-2011 (CUB-200-2011), show that the newly proposed method outperforms in accuracy several state-of-the-art weakly supervised classification models

    Research on stereo vision technology based on improved Region growing method

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    Image segmentation is the cornerstone of image analysis and image processing, its main difficulty is the ill-posedness of image segmentation. The region growing method is the most commonly used method in image segmentation. Its advantages are fast calculation speed, lower algorithm difficulty, and easy understanding. This article uses the area growing algorithm and TOF combined with binocular fusion technology. Discussed how to select the seed points in the region growing method. The algorithm proposed in this paper has high accuracy and high matching quality in the boundary area of the object and the area with large difference in depth. It has both matching time and reliability. It has good results and overcomes the limitations of the active and passive distance methods in the vision system

    Determination of Sulfonamide Residues in Food by Capillary Zone Electrophoresis with On-Line Chemiluminescence Detection Based on an Ag(III) Complex

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    The presence of sulfonamide (SA) residues in foods is largely due to the raising of animals with sulfonamide antibiotics added or polluted feedstuff. In this paper, a sensitive method was developed for the determination of the residues of three sulfonamides in animal-derived food; the SAs include sulfadimidine (SDD), sulfadiazine (SDZ), and sulfathiazole (STZ). The method is based on capillary zone electrophoresis (CE) with online chemiluminescence (CL) detection, using an Ag(III) complex as an oxidant. These SAs have an inhibiting effect on the Ag(III)–luminol CL reaction. The electrophoretic buffer is 12.0 mM sodium borate. Under a set of optimized conditions, the linear ranges for the detections were found to be 10.0–200 µg·mL−1 for SDD and SDZ, and 2.0–50.0 µg·mL−1 for STZ. The detection limits were 2.75, 3.14, and 0.65 µg·mL−1 for SDD, SDZ, and STZ, respectively. Relative standard deviations (RSD) for the peak heights were between 2.1% and 2.8% (n = 7). The proposed method was used in the analysis of the SAs in samples from pork meat, chicken meat, and milk, showing satisfactory detection results. A reaction mechanism was also proposed for the Ag(III)–luminol–SA CL reactions. The method has potential applications for the monitoring of residue levels of the three SAs in food, providing food safety data
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