Trailer truck trajectory optimization: the transportation of components for the Airbus A380

European aircraft manufacturer, Airbus, has started a program to develop the largest aircraft ever built, the Airbus A380, which would be able to carry between 550 to 800 passengers on two decks. The six components of the airplane are to be produced in different European cities. They need to be transported from these cities to Toulouse, France, for assembly, and several means of transportation have been investigated. The sizes of the freights, the length of the itinerary, and the narrowness of the critical passages constitute a challenge that classical transportation techniques in the domain of oversized convoys cannot easily overcome. Therefore, Airbus and the French national agency in charge of road management launched a research and development project divided into two parts. The objective of the first part is to adapt functions first to develop for mobile robots to the complex kinematics of trailer-truck systems and integrating these functions into a software platform. The second part of the project aims to define and develop a computer-aided driving system on board the vehicles in order to help the drivers carry out their task. This paper provides a brief overview of the state of the art in trajectory planning for mobile robots and vehicles, and discusses the development of original solutions to address both the kinematic complexity of one of the vehicles and the need to optimize the distance to obstacles.     

Surface oxidation of silicon carbide: quantitative measurement and Rh effect

The oxidation degree of a commercial silicon carbide (SiC) powder was studied by means of Fourier transform infrared spectroscopy, using the intensity of the δ (SiO₂) band at 450 cm⁻¹ for measurements. Results are related to data obtained by LECO and gravimetric measurements. The influence of water in oxygen on the rate of the oxidation process was particularly examined. It was found that water alone had an oxidizing efficiency and that its mixture with oxygen increased the effect of the latter. The presence of Rh particles on SiC promoted the formation of SiO₂. However, as shown by the IR study of CO adsorption, this formation embedded the metal particles. This effect can be avoided by loading Rh on a precalcined SiC sample.     

Fuel-rich catalytic combustion of methane in zero emissions power generation processes

A novel catalytic combustion concept for zero emissions power generation has been investigated. Catalysts consisting of Rh supported on ZrO₂, Ce-ZrO₂ or -Al₂O₃ were prepared and tested under fuel-rich conditions, i.e. for catalytic partial oxidation (CPO) of methane. The experiments were performed in a subscale gas-turbine reactor operating at 5 bar with exhaust gas-diluted feed mixtures.

The catalyst support material was found to influence the light-off temperature significantly, which increased in the following order Rh/Ce-ZrO₂ < Rh/ZrO₂ < Rh/-Al₂O₃. The Rh loading, however, only had a minor influence. The high activity of Rh/Ce-ZrO₂ is probably related to the high dispersion of Rh on Ce-ZrO₂ and the high oxygen mobility of this support compared to pure ZrO₂. The formation of hydrogen was also found to increase over the catalyst containing ceria in the support material.     

Exhaust Gas Catalysts for Heavy-Duty Applications: Influence of the Pd Particle Size and Particle Size Distribution on the Combustion of Natural Gas and Biogas

In this study, an experimental investigation concerning exhaust gas catalysts for heavy-duty diesel engines fuelled by natural gas or biogas is presented. Miniature monoliths, 2.5 wt% Pd/Al₂O₃, have been prepared, characterised and tested. Various methods have been used in order to obtain different palladium particle sizes, including incipient wetness and microemulsion technique. Crystallite sizes between 2 and 40 nm were obtained. We observed that the metal particle size influences the activity for methane oxidation. Moreover, the homogeneity of the active material was found to affect the reaction rate.     

Deactivation and Regeneration of Spent Three-Way Automotive Exhaust Gas Catalysts (TWC)

The effect of oxidation, oxy-chlorination and reduction treatments at elevated temperatures on the dispersion of palladium (Pd) and rhodium (Rh) for commercially aged three-way automotive exhaust gas catalysts (TWC) has been investigated. The catalytic activity of treated samples was compared with a reference sample, which was taken from the corresponding aged TWC and tested using a mini-cuts reactor simulating real driving conditions. In the case of oxygen, the improvement of the noble metal dispersion on the catalysts was dependent on the noble metal loading and the degree of metal sintering. Adding chlorine to the oxygen atmosphere facilitates the restructuring of the metals with an improved increase in the noble metal dispersion. The temperature and the composition of the gas used during these thermal treatments proved to be of importance not only to increase the metal dispersion, but also to prevent possible losses of noble metals, in the form of volatile MO _x Cl _y compounds. TEM-EDS techniques indicated changes in the size of the largest noble metal agglomerates of up to 100 nm in size after thermal gas treatment. BET porosity and XRD analyses were employed to investigate restructuring of the washcoat and showed a decrease in pore size distribution and an increase in surface area.     

Microemulsions in the preparation of highly active combustion catalysts

Catalytic activity in combustion of toluene in toluene–air mixtures and physical–chemical properties of platinum catalysts prepared from reverse microemulsions (water-in-oil) and by classical impregnation from water solutions of H₂PtCl₆ were studied. Microemulsion catalysts were more active than those prepared classically from water solutions. Size of Pt in classically impregnated catalysts was three times higher than that of catalysts prepared from microemulsions. In case of microemulsion preparation method, platinum is located near the pellet surface or its position in the pellet can be optimised. The effect of oil used in microemulsion system seems to be negligible for the activity of the catalysts with 0.1 wt.% Pt.     

Evidence for Diffusion-Controlled Hydrocarbon Selectivities in the Fischer�CTropsch Synthesis Over Cobalt Supported on Ordered Mesoporous Silica

A series of four cobalt-based catalysts (two of which promoted with ruthenium) supported on SiO₂ or SBA-15 were prepared and tested in the Fischer?CTropsch synthesis at industrially relevant process conditions (483 K, 20 bar, H₂/CO ratio = 2.1, pellet size: 53?C90 ??m). The catalysts were characterized by N₂-adsorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR), H₂-chemisorption and transmission electron microscopy (TEM). Ru as promoter enhanced the activity but not the selectivity to long-chain hydrocarbons ( $ {\text{S}}_{{{\text{C}}_{ 5+ } }} $ ). The $ {\text{S}}_{{{\text{C}}_{ 5+ } }} $ values of the SBA-supported catalysts were very low, especially at low conversion levels (i.e. low water partial pressure), suggesting that CO diffusion limitation increased the H₂/CO ratio inside the 1-dimensional (1-D) porous network. A superimposition of the selectivity results on the correlations found in our recent study, derived for Co-based catalysts supported on ??-Al₂O₃, ??-Al₂O₃ and TiO₂ free from diffusion limitations, was made. While the SiO₂-supported catalysts with a 3-D porous structure followed the correlations, the SBA-catalysts deviated significantly at low conversions, giving a further indication that the selectivity results of these catalysts were affected by CO diffusion limitations. Hence, it may be concluded that the kinetically significant diffusion distances (i.e. those long enough to cause an intrapore H₂/CO ratio higher than that of the bulk gas phase) are probably much shorter for 1-D porous networks than for conventional 3-D supports. This is explained by a significantly lower effective diffusivity in 1-D porous networks. The potential of using the correlations between non-ASF distributed hydrocarbons and C₅₊, to give insight on the occurrence of diffusion limitations, was confirmed by superimposing data from the literature that were anticipated to be influenced by CO diffusion limitations.     

A new 34-kilodalton isoform of human fibroblast growth factor 2 is cap dependently synthesized by using a non-AUG start codon and behaves as a survival factor

Four isoforms of human fibroblast growth factor 2 (FGF-2) result from alternative initiations of translation at three CUG start codons and one AUG start codon. Here we characterize a new 34-kDa FGF-2 isoform whose expression is initiated at a fifth initiation codon. This 34-kDa FGF-2 was identified in HeLa cells by using an N-terminal directed antibody. Its initiation codon was identified by site-directed mutagenesis as being a CUG codon located at 86 nucleotides (nt) from the FGF-2 mRNA 5' end. Both in vitro translation and COS-7 cell transfection using bicistronic RNAs demonstrated that the 34-kDa FGF-2 was exclusively expressed in a cap-dependent manner. This contrasted with the expression of the other FGF-2 isoforms of 18, 22, 22.5, and 24 kDa, which is controlled by an internal ribosome entry site (IRES). Strikingly, expression of the other FGF-2 isoforms became partly cap dependent in vitro in the presence of the 5,823-nt-long 3' untranslated region of FGF-2 mRNA. Thus, the FGF-2 mRNA can be translated both by cap-dependent and IRES-driven mechanisms, the balance between these two mechanisms modulating the ratio of the different FGF-2 isoforms. The function of the new FGF-2 was also investigated. We found that the 34-kDa FGF-2, in contrast to the other isoforms, permitted NIH 3T3 cell survival in low-serum conditions. A new arginine-rich nuclear localization sequence (NLS) in the N-terminal region of the 34-kDa FGF-2 was characterized and found to be similar to the NLS of human immunodeficiency virus type 1 Rev protein. These data suggest that the function of the 34-kDa FGF-2 is mediated by nuclear targets.     

Ce-promoted Co/Al2O3 catalysts for Fischer–Tropsch synthesis

The effect of ceria promotion on the performance of Co/Al₂O₃ catalyst was evaluated in a high pressure fixed bed reactor for Fischer–Tropsch (FT) synthesis at close industrial conditions. Ce–Al₂O₃ supports with a molar ratio of Al/Ce = 8 were prepared by two different methods: one by co-precipitation of cerium and aluminum precursors in water-in-oil microemulsion and the other one by aqueous impregnation of cerium nitrate on commercial alumina. These supports, together with the unmodified alumina carrier, were used to prepare four cobalt-based catalysts. These catalysts were characterized by XRD, SEM, EDX, TEM, N₂ adsorption/desorption, TPR and chemisorption techniques. The results show that the presence of CeO₂ on the surface of the support favors the reducibility of cobalt oxides with a shift down in reduction temperature of about 70 °C. The catalytic evaluation of the catalysts revealed that cerium addition by impregnation increases the activity and selectivity to C₅₊ catalyst in FTS. The catalyst synthetized by microemulsion show lower catalytic performance. Nevertheless, the catalytic property of this material can be improved by increasing the crystalline micro-domains size of CeO₂.     

Deactivation and regeneration of spent three-way automotive exhaust gas catalysts (TWC)

Topics in Catalysis - The effect of oxidation, oxy-chlorination and reduction treatments at elevated temperatures on the dispersion of palladium (Pd) and rhodium (Rh) for commercially aged...