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The electronic structure has a profound effect on the performance of photocatalyst. In this study, the electronic structure of Bi2WO6 is calculated with density functional theory (DFT). The CoWO4@Bi2WO6 Z-scheme heterojunction was prepared by one-step hydrothermal method. XRD, XPS, SEM, and TEM were used to demonstrate the successful preparation of the composites. Ciprofloxacin was used to test the performance of the catalysts. The results showed that the 1:5 CBWO has the best degradation performance, which was 5 and 9 times than that of BWO and CWO within 120 min, respectively. The intervention of DFT theory provides a reference for the selection of loading material and one-step hydrothermal method can save energy and produce high yield of materials. Therefore, this study has a good guiding significance for the modification of Bi2WO6 and other photocatalytic materials in the future. [ABSTRACT FROM AUTHOR]

Bi/Bi4O5Br2 composite photocatalysts with different loading were prepared by ethylene glycol reduction method. The successful construction of the composite was confirmed by X-ray diffraction, Fourier transform infrared, scanning electron microscope, photoluminescence, UV–Vis diffuse reflection spectroscopy, and X-ray photoelectron spectroscopy. The prepared Bi/Bi4O5Br2 composite can degrade the colored dye RhB and the colorless substance BPA under simulated visible light. The catalytic activity of the composite is obviously improved compared with that of the pure substance, and the photocatalytic performance of 5% loading of composite sample is the best. Through the experiments of photoluminescence spectrum and fluorescence decay curve, it is confirmed that the photo-generated carrier separation efficiency of 5% loading of composite sample is the highest. Radical trapping experiments show that h+ plays a major role. The improvement of photocatalytic activity of the composite is attributed to the plasmon resonance effect of Bi, which promotes the transfer and separation of semiconductor interface charge. The composite material has good cycle stability, which provides a research idea for the photocatalytic treatment of wastewater. [ABSTRACT FROM AUTHOR]

The gamma distribution is one of the most important parametric models in probability theory and statistics. Although a multitude of studies have theoretically investigated the properties of the gamma distribution in the literature, there is still a serious lack of tailored statistical tools to facilitate its practical applications. To fill the gap, this paper develops a comprehensive R package for the gamma distribution. In specific, the R package focuses on the following three important tasks: generate the gamma random variables, estimate the model parameters, and construct statistical limits, including confidence limits, prediction limits, and tolerance limits based on the gamma random variables. The proposed package encompasses the state-of-the-art methods of the gamma distribution in the literature and its usage is illustrated by a real application. [ABSTRACT FROM AUTHOR]

V‐doped WO3 microspheres composed of nanorods radially grown from the center were fabricated via a simple hydrothermal method. The as‐obtained products were characterized by several techniques such as X‐ray powder diffraction (XRD), energy dispersive spectrometer (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectrum, and Brunauer–Emmett–Teller (BET). It was found that V atoms were incorporated inside the hexagonal WO3 lattice. On the basis of time‐dependent experiments, the formation mechanism for the as‐prepared V‐doped WO3 micro‐nanostructures was discussed. In addition, the catalytic properties of the synthesized material on the thermal decomposition of ammonium perchlorate (AP) were evaluated by thermal gravimetric and differential thermal analysis (TG/DTA), which showed the thermal decomposition temperatures of AP in the presence of 1, 2, and 4 wt% of V‐doped WO3 micro‐nanostructures were reduced to 399, 393, and 380°C, respectively. [ABSTRACT FROM AUTHOR]

In this study, a novel oxygen vacancy-rich BiOCl/ZnMoO4 composites were successfully prepared by a simple two-step method. Experimental results indicated that the content of BiOCl with oxygen vacancies played an important role in photocatalytic performance of OBZM heterostructures. OBZM-5 exhibited a highly enhanced photocatalytic activity under visible light irradiation compared to pure BiOCl, Ov-BiOCl, ZnMoO4 and other OBZM composites, which can be attributed to the efficient separation and transfer of photogenerated charge carrier. The photocatalytic degradation efficiency of rhodamine B (RhB) can reach 99% within 40 min and almost all of norfloxacin (NOR) can be degradated after 100 min by OBZM-5. In addition, OBZM-5 displayed a good stability during the photocatalytic process, which favored a long-term use. Moreover, a possible photocatalytic mechanism was proposed based on the active species trapping experiments and electron spin resonance (ESR) tests, verifying that the photogenerated holes (h+) and ·O2− radicals were the dominating active species. [ABSTRACT FROM AUTHOR]

This study proposes an efficient approach to detect one or more change points for gamma distribution. We plug a closed-form estimator into the gamma log-likelihood function to obtain a sharp approximation to the maximum of log-likelihood. We further derive a closed form calibration of approximate likelihood which is asymptotically equivalent to the exact log-likelihood. This circumvents iterative optimization procedures to find maximum likelihood estimates which can be a burden in detecting multiple change points. The simulation study shows that the approximation is accurate and the change points can be detected much faster. Two case studies on the time between events arising from industrial accidents are presented and extensively investigated. [ABSTRACT FROM AUTHOR]

Many large organizations have developed ambitious programs to build reliability databases by collecting field failure data from a large variety of components. To make the database concise, only the number of component replacements in a component position during an operation time interval is reported in these databases. This leads to time-censoring in the aggregate failure data. Statistical inference for the time-censored aggregate data is challenging, because the likelihood function based on some common lifetime distributions can be intractable. In this study, we propose a general parametric estimation framework for the aggregate data. We first use the gamma distribution and the Inverse Gaussian (IG) distribution to model the aggregate data. Bayesian inference for the two models is discussed. Unlike the gamma/IG distribution, other lifetime distributions involve multiple integrals in the likelihood function, making the standard Bayesian inference difficult. To address the estimation problem, an approximate Bayesian computation algorithm that does not require evaluating the likelihood function is proposed, and its performance is assessed by simulation. As there are several candidate distributions, we further propose a model selection procedure to identify an appropriate distribution for the time-censored aggregate data. A real aggregate dataset extracted from a reliability database is used for illustration. [ABSTRACT FROM AUTHOR]

Reservoirs have been widely constructed all over the world in recent years to alleviate the shortage of water resources. Nevertheless, the assessment method of water quality and its trophic status needs to be developed. In this study, water quality parameters of a newly constructed shallow reservoir were regularly monitored for a period of two years, which is used as a major drinking water source of Shanghai, China. Furthermore, the trophic state indices of the reservoir were investigated based on literature and evaluated with the two-year field data. The results indicated that the studied reservoir is reaching the mesotrophic–eutrophic boundary, where further nutrient enrichment could cause water quality degradation; total phosphorus is the limiting nutrient for algal growth in the studied reservoir. Results of the study can help operators understand change and status of water quality of the reservoir and provide valuable data demonstrating variation of water quality indicators and trophic characteristics in shallow reservoirs or lakes. [ABSTRACT FROM AUTHOR]

The prediction of remaining useful life (RUL) is a critical component of prognostic and health management for industrial systems. In recent decades, there has been a surge of interest in RUL prediction based on degradation data of a well‐defined degradation index (DI). However, in many real‐world applications, the DI may not be readily available and must be constructed from complex source data, rendering many existing methods inapplicable. Motivated by multivariate sensor data from industrial induction motors, this paper proposes a novel prognostic framework that develops a nonlinear DI, serving as an ensemble of representative features, and employs a similarity‐based method for RUL prediction. The proposed framework enables online prediction of RUL by dynamically updating information from the in‐service unit. Simulation studies and a case study on three‐phase industrial induction motors demonstrate that the proposed framework can effectively extract reliability information from various channels and predict RUL with high accuracy. [ABSTRACT FROM AUTHOR]