In the helicopter transmission systems, it is important to monitor and track the tooth damage evolution using lots of sensors and detection methods. This paper develops a novel approach for sensor selection based on p...In the helicopter transmission systems, it is important to monitor and track the tooth damage evolution using lots of sensors and detection methods. This paper develops a novel approach for sensor selection based on physical model and sensitivity analysis. Firstly, a physical model of tooth damage and mesh stiffness is built. Secondly, some effective condition indicators （Cls） are presented, and the optimal Cls set is selected by comparing their test statistics according to Mann-Kendall test. Afterwards, the selected CIs are used to generate a health indicator （HI） through sen slop estimator. Then, the sensors are selected according to the monotonic relevance and sensitivity to the damage levels. Finally, the proposed method is verified by the simulation and experimental data. The results show that the approach can provide a guide for health monitor- ing of helicopter transmission systems, and it is effective to reduce the test cost and improve the system＇s reliability.展开更多
High nutritional content coupled with low cost and ease of purchase justifies the frequent use of chicken eggs. Even with technological innovations in the production, storage, and distribution of eggs, food poisoning ...High nutritional content coupled with low cost and ease of purchase justifies the frequent use of chicken eggs. Even with technological innovations in the production, storage, and distribution of eggs, food poisoning continues to occur. Therefore, in the present study, we 1) evaluated the microbiological profile and the hygienic and sanitary quality of eggs commercialized in town fairs and markets and 2) verified whether there is any correlation between microbiological results and commercialization conditions. Thirty-six samples were collected from six municipalities in the region of Rec?ncavo from Bahia, Brazil. The hygienic and sanitary conditions were analyzed by quantifying the total coliforms, E. coli, mesophilic and psychrotrophic microorganisms, molds, and yeasts, and by the presence of Salmonella sp. The observational analysis showed that 91% and 68% of the samples in town fairs and markets, respectively, did not comply with the requirements of the current Brazilian legislation. There was no significant difference in the microbiological profile among samples from the fairs and markets. Several samples presented relevant significant values, indicating inadequate hygienic conditions and fecal contamination. Salmonella sp. was found in one sample. There was co-relationship between microorganism count and the variables “external dirt”, “external stains”, and “closeness to other products”, with high concentrations of total coliforms and E. coli in the non-conforming samples. Although no limits exist for mold and yeast counts, the presence of fungi makes the product unfit for consumption. Thus, the commercialization of eggs would benefit from more attention and supervision by the relevant authorities.展开更多
基金supported by the National Natural Science Foundation of China (No. 51175502)
文摘In the helicopter transmission systems, it is important to monitor and track the tooth damage evolution using lots of sensors and detection methods. This paper develops a novel approach for sensor selection based on physical model and sensitivity analysis. Firstly, a physical model of tooth damage and mesh stiffness is built. Secondly, some effective condition indicators （Cls） are presented, and the optimal Cls set is selected by comparing their test statistics according to Mann-Kendall test. Afterwards, the selected CIs are used to generate a health indicator （HI） through sen slop estimator. Then, the sensors are selected according to the monotonic relevance and sensitivity to the damage levels. Finally, the proposed method is verified by the simulation and experimental data. The results show that the approach can provide a guide for health monitor- ing of helicopter transmission systems, and it is effective to reduce the test cost and improve the system＇s reliability.
文摘High nutritional content coupled with low cost and ease of purchase justifies the frequent use of chicken eggs. Even with technological innovations in the production, storage, and distribution of eggs, food poisoning continues to occur. Therefore, in the present study, we 1) evaluated the microbiological profile and the hygienic and sanitary quality of eggs commercialized in town fairs and markets and 2) verified whether there is any correlation between microbiological results and commercialization conditions. Thirty-six samples were collected from six municipalities in the region of Rec?ncavo from Bahia, Brazil. The hygienic and sanitary conditions were analyzed by quantifying the total coliforms, E. coli, mesophilic and psychrotrophic microorganisms, molds, and yeasts, and by the presence of Salmonella sp. The observational analysis showed that 91% and 68% of the samples in town fairs and markets, respectively, did not comply with the requirements of the current Brazilian legislation. There was no significant difference in the microbiological profile among samples from the fairs and markets. Several samples presented relevant significant values, indicating inadequate hygienic conditions and fecal contamination. Salmonella sp. was found in one sample. There was co-relationship between microorganism count and the variables “external dirt”, “external stains”, and “closeness to other products”, with high concentrations of total coliforms and E. coli in the non-conforming samples. Although no limits exist for mold and yeast counts, the presence of fungi makes the product unfit for consumption. Thus, the commercialization of eggs would benefit from more attention and supervision by the relevant authorities.
