Robust diagnosis to measurement uncertainties using bond graph approach: Application to intelligent autonomous vehicle

This paper deals with robust bond graph model-based fault detection and isolation to improve the robustness of the diagnosis system in presence of measurements and parameters uncertainties. We develop a procedure of measurement uncertainties modeling directly on the graph. By using the structural and causal properties of the bond graph, the robust diagnosis is performed. The interest of the developed methodology consists in using the graphical tool not only for measurement uncertainties modeling, but also for designing robust fault detection and isolation algorithms. Moreover, this method can be easily automated. The developed approach is validated by an application to an electromechanical traction system of intelligent autonomous vehicle.     

Cemented paste backfill of sulphide-rich tailings: Importance of binder type and dosage

In this study, the influence of binder type and dosage on the mechanical properties and microstructure of cemented paste backfill (CPB) was investigated using ordinary Portland cement (OPC), Portland composite cement (PCC) and sulphate resistant cement (SRC). The CPB samples of OPC and PCC were observed to lose their unconfined compressive strengths (UCSs) after 56 days. This could be associated with the sulphide moiety of the tailings, i.e. the attack on hydration products by sulphate and acid internally generated via the oxidation of pyrite present. In this respect, those CPB samples of sulphate resistant-based cements (SRC and a mix of OPC and SRC) maintained good long-term strengths and stability (i.e. no loss of strength). Increasing binder dosage (5–7 wt.%) improved the UCSs of CPB samples up to 1.9-fold with no loss of strength at >5 wt.%. Decreasing water-to-cement ratio appeared to produce a beneficial effect on the UCSs of CPB samples. SEM studies have provided further insight into the microstucture of CPB and confirmed the deleterious formation of gypsum as the expansive phase. These findings have demonstrated the practical importance of binder type/dosage and water-to-cement ratio for the short- and long-term mechanical performance of CPB.     

Modeling the effect of algal dynamics on arsenic speciation in Lake Biwa

Algae reduce and methylate arsenate and the end product of the reaction is correlated to their growth rate. At slow growth rates, dimethylarsinate (DMA) is produced, and at fast growth rates arsenite (As(III)) is produced. Previous work has linked this phenomenon to the phosphorus luxury uptake mechanism of algae, and a model was developed for the process (Hellweger et al. Limnol. Oceanogr. 2003, 48, 2275). This paper presents the integration of that process model for arsenic transformation by algae into a full ecological model and application to Lake Biwa, Japan. The model application allows for a quantitative analysis of the field data, consistent with the process model and the ecological dynamics of the lake. The newly developed ecological model includes a variable phytoplankton composition, which is needed to simulate luxury uptake. This is in contrast to most existing ecological models, which typically assume a fixed "Redfield" composition. The model adequately reproduces the observed ecology of Lake Biwa, including the rapid uptake of phosphate by phytoplankton without immediate growth (luxury uptake) following lake overturn. The model also reproduces the observed arsenic speciation, including the gradual appearance of DMA during the summer and peaks in As(III) concentration at the onset of spring and fall algal blooms.     

Crosslinked TS-1 as stable catalyst for the Beckmann rearrangement of cyclohexanone oxime

Crosslinked TS-1 zeolite materials have been studied in the gas phase Beckmann rearrangement reaction of cyclohexanone oxime to ε-caprolactam. Crosslinking of the zeolite particles resulted in the formation of an additional mesoporosity leading to increased activity in the Beckmann rearrangement reaction. The increased activity can be correlated with the newly created mesopore surface. Possibly more important, together with increased catalytic activity of the materials, the deactivation behavior of the catalysts is very significantly improved.     

Detailed study on the use of electrospray mass spectrometry to investigate speciation in concentrated silicate solutions

Silicate speciation in aqueous solutions containing tetraalkylammonium hydroxide as template is examined by electrospray mass spectrometry. A thorough study has been carried out to define and optimize the conditions of analysis for a highly concentrated reaction solution of inorganic species--in this case, silicate oligomers--by using different ion source designs. The results reveal specific advantages with respect to the detected species. Condensation of monomers leads to oligomeric units that condense further in different reaction steps to larger species. Potential gas-phase reactions that can disturb characterization of the formed silicate species were intensively investigated and characterized. One reaction that plays a key role is the alkoxylation of Si-OH groups that is caused by two different reactions: first, a reaction of methanolate from the solvent and, second, by the involvement of the template salt, tetramethylammonium hydroxide.