Interfacial reactions between impurities and slag onset of Si purification by slag addition

The interfacial reactions between impurities (Al and Ti) and slag onset of Si purification by 51 mol% SiO2–34 mol% CaO–15 mol% MgO slag addition were studied to enhance impurity removal efficiency from Si. The Al distribution behavior at the Si/Slag interface was investigated; a short reaction time (10 s) resulted in the formation of successive SiO2–CaO–MgO–Al2O3 layers in the slag with a thickness of 10 µm; increasing the reaction time (60 s) resulted in the entire ternary slag being changed into SiO2–CaO–MgO–Al2O3 quaternary slag due to the diffusion of Al2O3. It was shown that the highest impurity removal rate of Al could be achieved at the onset of the slag refining process. Based on the Ti distribution at the Si/slag interface, the slag refinement with 51 mol% SiO2–34 mol% CaO–15 mol% MgO had no effect on Ti removal.

Robust LPV models identification approach based on shifted asymmetric Laplace distribution

This paper focuses on the robust parameters estimation algorithm of linear parameters varying (LPV) models. The classical robust identification techniques deal with the polluted training data, for example, outliers in white noise. The paper extends this robustness to both symmetric and asymmetric noise with outliers to achieve stronger robustness. Without the assumption of Gaussian white noise pollution, the paper employs asymmetric Laplace distribution to model broader noise, especially the asymmetrically distributed noise, since it is an asymmetric heavy-tailed distribution. Furthermore, the asymmetric Laplace (AL) distribution is represented as the product of Gaussian distribution and exponential distribution to decompose this complex AL distribution. Then, a shifted parameter is introduced as the regression term to connect the probabilistic models of the noise and the predict output that obeys shifted AL distribution. In this way, the posterior probability distribution of the unobserved variables could be deduced and the robust parameters estimation problem is solved in the general Expectation Maximization algorithm framework. To demonstrate the advantage of the proposed algorithm, a numerical simulation example is employed to identify the parameters of LPV models and to illustrate the convergence.

The Aluminum Distribution and Translocation in Two Citrus Species Differing in Aluminum Tolerance

Background: Many citrus orchards of south China suffer from soil acidification, which induced aluminum (Al) toxicity. The Al-immobilization in vivo is crucial for Al detoxification. However, the distribution and translocation of excess Al in citrus species were not well illustrated.Results: The seedlings of ‘Xuegan’ [Citrus sinensis (L.) Osbeck] and ‘Shatianyou’ [Citrus grandis (L.) Osbeck] that differed in Al tolerance were hydroponically treated with nutrient solution (Control) or supplemented by 1.0 mM Al3+ (Al toxicity) for 21 days after three months of pre-culture. The Al distribution at the tissue level of citrus species following the order: lateral roots > primary roots > leaves > stems. The fragmentation of fresh lateral roots revealed the ratio of Al distribution at the cell wall, cell organelle and cytoplasmic supernatant was about 8:2:1 of two citrus species under Al stress. Besides, the Al distribution at the lateral root cell wall components suggested the pectin is the most Al-accumulating site in citrus species. Compared to C. grandis, C. sinensis had a significantly higher Al concentration on the cell wall of lateral roots whereas remarkably lower Al levels on the leaves and stems. Furthermore, the Al translocation revealed by the absorption kinetics of the cell wall demonstrated that C. sinensis had a higher Al retention and stronger Al affinity on the root cell wall than C. grandis. According to the FTIR (Fourier transform infrared spectroscopy) analysis, the Al distribution and translocation might be affected by modifying the structure and components of the citrus lateral root cell wall. Conclusions: A higher Al-retention, mainly targeted by the pectin of the root cell wall, and a lower Al translocation efficiency from roots to shoots contributed to a higher Al tolerance of C. sinensis than C. grandis.

Influence of the ultrasonic-assisted synthesis on Al distribution in MOR zeolite. From gel to resulting material

Two Al-rich mordenite samples were prepared by the same synthesis procedure except for the activation of the gel for which classical stirring and ultrasonic pretreatment was used. The organization of...