Deep Bayesian survival analysis of rail useful lifetime

Reliable estimation of rail useful lifetime can provide valuable information for predictive maintenance in railway systems. However, in most cases, lifetime data is incomplete because not all pieces of rail experience failure by the end of the study horizon, a problem known as censoring. Ignoring or otherwise mistreating the censored cases might lead to false conclusions. Survival approach is particularly designed to handle censored data for analysing the expected duration of time until one event occurs, which is rail failure in this paper. This paper proposes a deep Bayesian survival approach named BNN-Surv to properly handle censored data for rail useful lifetime modelling. The proposed BNN-Surv model applies the deep neural network in the survival approach to capture the non-linear relationship between covariates and rail useful lifetime. To consider and quantify uncertainty in the model, Monte Carlo dropout, regarded as the approximate Bayesian inference, is incorporated into the deep neural network to provide the confidence interval of the estimated lifetime. The proposed approach is implemented on a four-year dataset including track geometry monitoring data, track characteristics data, various types of defect data, and maintenance and replacement (M&R) data collected from a section of railway tracks in Australia. Through extensive evaluation, including Concordance index (C-index) and root mean square error (RMSE) for evaluating model performance, as well as a proposed CW-index for evaluating uncertainty estimations, the effectiveness of the proposed approach is confirmed. The results show that, compared with other commonly used models, the proposed approach can achieve the best concordance index (C-index) of 0.80, and the estimated rail useful lifetimes are closer to real lifetimes. In addition, the proposed approach can provide the confidence interval of the estimated lifetime, with a correct coverage of 81% of the actual lifetime when the confidence interval is 1.38, which is more useful than point estimates in decision-making and maintenance planning of railroad systems.Railway Engineerin

Built Environment Impacts on Rural Residents’ Daily Travel Satisfaction

The rapid urbanization in China urges scholars to investigate the impacts of built environment on the level of travel satisfaction of rural residents to improve their quality of life and make planning exercises more human-centric. This study samples six villages out of the 25 top rural areas in Chengdu, Sichuan, China, as the research object and constructs a structural equation model to explore the direct and indirect impacts of the built environment on daily travel satisfaction of rural residents. The research finds that building density (0.609), road density (0.569), the number of accessible markets (0.314), and private car ownership (0.02) have significant positive impacts on travel satisfaction. Public transport (−0.063) has a direct negative impact on travel satisfaction. Consequently, in order to further improve travel satisfaction, construction departments and rural planners should improve the building and road densities of new rural areas and increase the number of accessible markets. The convenience of rural public transport services also needs improvement.Design & Construction Managemen

A Chitinase from Aeromonas veronii CD3 with the Potential to Control Myxozoan Disease

Background: The class Myxosporea encompasses about 2,400 species, most of which are parasites of fish and cause serious damage in aquaculture. Due to the concerns about food safety issues and limited knowledge of Myxozoa life cycle and fish immune system, no chemicals, antibiotics or immune modulators are available to control myxozoa infection. Therefore, little can be done once Myxozoa establishment has occurred. Methodology/Principal Findings: In this paper we isolated Aeromonas veronii CD3 with significant myxospore shell valve-degrading ability from pond sediment. A 3,057-bp full-length chitinase gene was consequently cloned, and the corresponding mature, recombinant chitinase (ChiCD3) produced by Escherichia coli had substantial chitinase activity. The deduced sequence of ChiCD3 contained one catalytic domain, two chitin-binding domains, and one putative signal peptide. ChiCD3 had an optimal activity at 50u degrees C and pH 6.0, and retained more than 50% of its optimal activity under warm water aquaculture conditions (similar to 30 degrees C and pH similar to 7.0). After incubation with ChiCD3, 38.0 +/- 4.8% of the myxospores had damaged shell valves, whereas myxospores incubated with commercially available chitinases remained intact. Conclusion/Significance: This study reveals a new strategy to control myxozoan disease. ChiCD3 that has capacity to damage the shell valve of myxospores can be supplemented into fish feed and used to control Myxozoa-induced diseases specifically

Changes in microbial communities and respiration following the revegetation of eroded soil

It is necessary to assess the responses of microbial communities and respiration to the revegetation of eroded soils for understanding the dynamics of soil carbon (C) pools and fluxes. In this study, three typical abandoned croplands (CL1, CL2 and CL3) and three secondary grasslands planted with Coronilla varia (GL1, GL2 and GL3) on the Loess Plateau of China were selected for sampling, and quantitative polymerase chain reaction (qPCR) and high-throughput sequencing were applied to intuitively discern differences in the soil bacteria and fungi. Our results showed that bacterial abundance in the abandoned croplands was 57 times higher than that of the secondary grasslands (P 0.05) in fungal abundance and microbial diversity were observed after 31 years of revegetation. We observed positive responses in Actinobacteria, Firmicutes, Zygomycota and Ciliophora and negative responses in Bacteroidetes and Planctomycetes to revegetation. In addition, the maximum soil microbial respiration was observed in the GL3 site (20.86 +/- 0.69 mg CO2-C kg(-1) soil d(-1)) followed by the GL1 site (19.97 +/- 0.65 mg CO2-C kg(-1) soil d(-1)), so revegetation significantly improved (P < 0.05) soil microbial respiration. Multiple stepwise regression analysis showed that dissolved organic carbon (DOC) explained up to 68.5% of the variation in soil microbial respiration, which indicated that the effects of changes in microbial properties in response to revegetation on soil microbial respiration were likely to be smaller than the potential effects of changes in the quality of organic matter. Labile organic matter is the primary rate-limiting factor for soil microbial respiration