Silkworm (Bombyx mori) (B. mori) is an economically important insect and a model species for Lepidoptera. It has been reported that feeding of low concentrations of titanium dioxide nanoparticles (TiO2 NPs) can improve feed efficiency and increase cocoon mass, cocoon shell mass, and the ratio of cocoon shell. However, high concentrations of TiO2 NPs are toxic. In this study, we fed B. mori with different concentrations of TiO2 NPs (5, 10, 20, 40, 80, and 160 mg/L) and investigated B. mori growth, feed efficiency, and cocoon quality. We found that low concentrations of TiO2 NPs (5 and 10 mg/L) were more effective for weight gains, with significant weight gain being obtained at 72 h (P < 0.05). TiO2 NPs at 20 mg/L or higher had certain inhibitory effects, with significant inhibition to B. mori growth being observed at 48 h. The feed efficiency was significantly improved at low concentrations of 5 and 10 mg/L for 14.6 and 13.1 %, respectively (P < 0.05). All B. mori fed with TiO2 NPs showed increased cocoon mass and cocoon shell mass; at 5 and 10 mg/L TiO2 NPs, cocoon mass was significantly increased by 8.29 and 9.39 %, respectively (P < 0.05). We also found that low concentrations (5 and 10 mg/L) of TiO2 NPs promoted B. mori growth and development, improved feed efficiency, and increased cocoon production, while high concentrations (20 mg/L or higher) of TiO2 NPs showed inhibitory effect to the B. mori. Consecutive feeding of high concentrations of TiO2 NPs led to some degrees of adaptability. This study provides a reference for the research on TiO2 NPs toxicity and the basis for the development of TiO2 NPs as a feed additive for B. mori.
Concurrent engineering has obtained increasing attention to solve the design problems of multidisciplinary systems. In practical engineering, there are epistemic uncertainties during whole design cycle of complex systems. Especially in earlier design phases, the effects of epistemic uncertainties are not usually easy to be quantified. It is because design information is insufficient. Furthermore, commonly used probability theory is also not suitable to be utilized. In this situation, epistemic uncertainties will be introduced unavoidably by mathematical models or simulation tools and may affect the performance of complex system significantly. To solve this problem, evidence theory is introduced and combined with the collaborative optimization method in this study. An evidence-based collaborative reliability optimization method is also proposed. Evidence theory is a powerful approach to handle epistemic uncertainties by Plausibility and Belief. Meanwhile, collaborative optimization is widely utilized in the concurrent design of complex systems. An aircraft conceptual design problem is utilized to show the application of the proposed method.
To evaluate the system reliability and the constellation availability of remote sensing satellite, in this study, a novel single satellite availability modeling and analysis strategy using on-orbit backup and ground added launch backup is proposed. First, considering the characteristics of remote sensing satellites, the calculation formulas of constellation availability are given in detail. Then, the process of system reliability modeling is also illustrated step by step. Finally, an availability evaluation example of remote sensing satellite constellation is introduced to show the effectiveness of the proposed method.
Reliability is one of the critical attributes for long life and high performance satellite. To deal with the limitation on satellite reliability analysis confronted in the past decades, a series of papers has been published recently by Saleh et al. In these papers, thousands of Earth-orbiting satellites successfully launched between 1990 and 2008 have been analyzed. This paper extends the statistical analysis of satellite reliability based on the same database. The satellite reliability is modeled using a modified Weibull extension distribution. The parametric estimation is carried out by utilizing the nonlinear least squares method. Finally, a comparative analysis is conducted on the fitting results of Weibull and modified Weibull extension distribution. The results demonstrate that the modified Weibull extension distribution is more accurate and flexible in modeling the satellite reliability than the traditional Weibull distribution. The accuracy and convenience of the modified Weibull extension distribution indicates its practical application in engineering designs.
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