Robust Point Cloud Registration for Aircraft Engine Pipeline Systems.

Aircraft engine systems are composed of numerous pipelines. It is crucial to regularly inspect these pipelines to detect any damages or failures that could potentially lead to serious accidents. The inspection process typically involves capturing complete 3D point clouds of the pipelines using 3D scanning techniques from multiple viewpoints. To obtain a complete and accurate representation of the aircraft pipeline system, it is necessary to register and align the individual point clouds acquired from different views. However, the structures of aircraft pipelines often appear similar from different viewpoints, and the scanning process is prone to occlusions, resulting in incomplete point cloud data. The occlusions pose a challenge for existing registration methods, as they can lead to missing or wrong correspondences. To this end, we present a novel registration framework specifically designed for aircraft pipeline scenes. The proposed framework consists of two main steps. First, we extract the point feature structure of the pipeline axis by leveraging the cylindrical characteristics observed between adjacent blocks. Then, we design a new 3D descriptor called PL-PPFs (Point Line-Point Pair Features), which combines information from both the pipeline features and the engine assembly line features within the aircraft pipeline point cloud. By incorporating these relevant features, our descriptor enables accurate identification of the structure of the engine's piping system. Experimental results demonstrate the effectiveness of our approach on aircraft engine pipeline point cloud data.

Biochar-Dual Oxidant Composite Particles Alleviate the Oxidative Stress of Phenolic Acid on Tomato Seed Germination.

Phenolic acid is a well-known allelochemical, but also a pollutant in soil and water impeding crop production. Biochar is a multifunctional material widely used to mitigate the phenolic acids allelopathic effect. However, phenolic acid absorbed by biochar can still be released. In order to improve the removal efficiency of phenolic acids by biochar, the biochar-dual oxidant (BDO) composite particles were synthesized in this study, and the underlying mechanism of the BDO particles in ameliorating p-coumaric acid (p-CA) oxidative damage to tomato seed germination was revealed. Upon p-CA treatment, the BDO composite particles application increased the radical length, radical surface area, and germination index by 95.0%, 52.8%, and 114.6%, respectively. Compared to using biochar or oxidants alone, the BDO particles addition resulted in a higher removal rate of p-CA and produced more O2•-, HO•, SO4•- and 1O2 radicals via autocatalytic action, suggesting that BDO particles removed phenolic acid by both adsorption and free radical oxidation. The addition of BDO particles maintained the levels of the antioxidant enzyme activity close to the control, and reduced the malondialdehyde and H2O2 by 49.7% and 49.5%, compared to the p-CA treatment. Integrative metabolomic and transcriptomic analyses revealed that 14 key metabolites and 62 genes were involved in phenylalanine and linoleic acid metabolism, which increased dramatically under p-CA stress but down-regulated with the addition of BDO particles. This study proved that the use of BDO composite particles could alleviate the oxidative stress of phenolic acid on tomato seeds. The findings will provide unprecedented insights into the application and mechanism of such composite particles as continuous cropping soil conditioners.

A Novel Belief Entropy for Measuring Uncertainty in Dempster-Shafer Evidence Theory Framework Based on Plausibility Transformation and Weighted Hartley Entropy.

Dempster-Shafer evidence theory (DST) has shown its great advantages to tackle uncertainty in a wide variety of applications. However, how to quantify the information-based uncertainty of basic probability assignment (BPA) with belief entropy in DST framework is still an open issue. The main work of this study is to define a new belief entropy for measuring uncertainty of BPA. The proposed belief entropy has two components. The first component is based on the summation of the probability mass function (PMF) of single events contained in each BPA, which are obtained using plausibility transformation. The second component is the same as the weighted Hartley entropy. The two components could effectively measure the discord uncertainty and non-specificity uncertainty found in DST framework, respectively. The proposed belief entropy is proved to satisfy the majority of the desired properties for an uncertainty measure in DST framework. In addition, when BPA is probability distribution, the proposed method could degrade to Shannon entropy. The feasibility and superiority of the new belief entropy is verified according to the results of numerical experiments.

[Wastewater pollution characteristics from typical intensive pig farms in the Pearl River Delta and its ecological risk assessment].

Based on the wastewater quality investigation data from March 2009 to November 2011, wastewater qualities from typical intensive pig farms were assessed in the Pearl River Delta by single and comprehensive pollution index model. The results showed that key pollutants of piggery wastewater were fecal coliform (FC), total phosphorus (TP), chemical oxygen demand (COD) and biochemical oxygen demand (BOD), with their average mass concentrations of 1.98 x 10(9) CFU.L-1, 158.61 mg.L-1, 5 608.68 mg.L-1 and 1984.34 mg.L-1, respectively; key pollutants of biogas slurry were FC, TP, ammonia nitrogen (NH+4 -N) and suspended substance (SS), with their average mass concentrations of 8. 10 x 10(6) CFU.L-1, 81.76 mg.L-1, 476.24 mg.L-1 and 464.58 mg.L-1, respectively. Under the effect of wastewater pollutants, environment surrounding of typical intensive pig farms was seriously polluted, which decreased gradually from piggery wastewater to biogas slurry, and comprehensive pollution indices were 11.41, 6.91, 5.27, respectively. The risk analysis showed that the high-risk wastewater could never be discharged directly and irrigated crops. After the anaerobic treatment, FC, TP, NH+4 -N and SS were still strong factors with the potential ecological risk in the biogas slurry. In the long run, the ecological risk still exists for direct discharge or irrigation of them, and it is necessary to apply further treatment.