Map management for robust long-term visual localization of an autonomous shuttle in changing conditions

Multimedia Tools and Applications - Changes in appearance present a tremendous problem for the visual localization of an autonomous vehicle in outdoor environments. Data association between the...     

Forthcoming papers

Announcements

Preliminary course programme international centre for mechanical Sciences     

Marvelous self-assembly of hierarchically nanostructured porous zirconium phosphate solid acids with high thermal stability

A hierarchical structure of thermally stable macroporous zirconium phosphate solid acids with supermicroporous walls was prepared by a simple self-assembly process from the precursors of zirconium propoxide and orthophosphoric acid solution. The macroporous structures are uniform with the diameters ranging from 300 to 800 nm, one-dimensional channel-like. The effect of surfactant Brij 56 on the formation of macroporous structures has been studied. The frameworks of the synthesized hierarchical zirconium phosphates are amorphous with Zr–O–P bonding, exhibiting remarkably high thermal stability (at least 800 °C), on the basis of the X-ray diffraction (XRD), N₂ adsorption, X-ray photoelectron spectroscopy (XPS) analysis, Fourier transform infrared (FT-IR) and ³¹P nuclear magnetic resonance (NMR) spectra. Larger quantities of Zr–OH and P–OH groups are observed besides surface hydroxyl groups, suggesting the presence of acidity and the possibility of surface functionalization for practical applications including catalysis. The macroporous zirconium phosphates with hierarchical structures could also be the potential and efficient catalyst supports for the design of the structured catalysts and reactors.     

Enthalpy recovery of gases issued from H2 production processes: Activity and stability of oxide and noble metal catalysts in oxidation reaction under highly severe conditions

Oxidation activity and stability under reaction was investigated for a series of mixed oxide catalysts, doped or not by a precious metal (Pd, Pt). The reaction feedstock, containing CO, H₂, CH₄, CO₂ and H₂O, simulated gases issued from H₂ production processes for fuel cells. Contrarily to conventional noble metal catalysts, mixed oxide samples present generally good stability under reaction at high temperature. The activities measured for the perovskite and hexaaluminate catalysts, are however largely lower than that of the reference Pd/Al₂O₃ catalyst. High activities were obtained after impregnation of 1.1 wt.% Pd or 0.8 wt.% Pt on the hexaaluminates samples. Even if Pd/Al₂O₃ was found to present a high activity, this sample suffered from drastic deactivation at 700 °C. Better stability were obtained on perovskite. Furthermore, doping hexaaluminate by Pt led to samples with good activities and high stability. Even if better activities were obtained by doping the hexaaluminate samples by Pd, the Pd/BaAl₁₂O₁₉ strongly deactivated, as it was previously observed for the reference catalyst. Interestingly, this Pd deactivation was not observed when Pd was impregnated on the Mn substituted hexaaluminate, leading to a stable and active catalyst. This suggests that it is possible to stabilize the palladium in its oxidized form at high temperature (700 °C) on the surface of some supports.     

How the risk of failure in lifetime of tempered glass depends on the size of NiS inclusions and heat soak test duration

The probability of breakage in service lifetime of heat-tempered glass panes contaminated by nickel sulfide inclusions is estimated with a multiscale micromechanically motivated statistical theory, which considers the effects of the heat soak test (HST). Short and long HSTs differently affect the phase transformation of NiS of diverse chemical composition, whose increase in volume can break the glass. The main hypothesis, corroborated by experiments, is that there is a lower limit for the size of NiS stones below which no crack can be initiated from the volumetric expansion. The catastrophic propagation of nucleated fractures in the long term is modeled through a rescaled critical stress intensity factor, which accounts for the subcritical crack propagation and the slow phase transformation of NiS. A parametric analysis evidences how the failure probability is strongly affected by these parameters, depending on the holding time in the HST. Tailored experimental activity is suggested for the proper calibration of the model.     

CPG-based control of a turtle-like underwater vehicle

This paper presents biologically inspired control strategies for an autonomous underwater vehicle (AUV) propelled by flapping fins that resemble the paddle-like forelimbs of a sea turtle. Our proposed framework exploits limit cycle oscillators and diffusive couplings, thereby constructing coupled nonlinear oscillators, similar to the central pattern generators (CPGs) in animal spinal cords. This paper first presents rigorous stability analyses and experimental results of CPG-based control methods with and without actuator feedback to the CPG. In these methods, the CPG module generates synchronized oscillation patterns, which are sent to position-servoed flapping fin actuators as a reference input. In order to overcome the limitation of the open-loop CPG that the synchronization is occurring only between the reference signals, this paper introduces a new single-layered CPG method, where the CPG and the physical layers are combined as a single layer, to ensure the synchronization of the physical actuators in the presence of external disturbances. The key idea is to replace nonlinear oscillators in the conventional CPG models with physical actuators that oscillate due to nonlinear state feedback of the actuator states. Using contraction theory, a relatively new nonlinear stability tool, we show that coupled nonlinear oscillators globally synchronize to a specific pattern that can be stereotyped by an outer-loop controller. Results of experimentation with a turtle-like AUV show the feasibility of the proposed control laws.     

Characterization of renal tumours based on Raman spectra classification

In this study, we propose to evaluate the potential of Raman spectroscopy (RS) to assess renal tumours at surgery. Different classes of Raman renal spectra acquired during a clinical protocol are discriminated using support vector machines classifiers. The influence on the classification scores of various preprocessing steps generally involved in RS are also investigated and evaluated in the particular context of renal tumour characterization. Encouraging results show the interest of RS to evaluate kidney cancer and suggest the potential of this technique as a surgical assistance during partial nephrectomy.     

Betriebliches Identitätsmanagement

Enterprise Identity Management Systems (EIdMS) are an IT-based infrastructure that needs to be integrated in various business processes and related infrastructures. Assessment and preparation of decisions for the introduction need to take the costs, benefits, and the organizational settings into consideration. A variety of methods for the evaluation and decision support of new IT (e. g. EIdMS) are discussed in the literature – however, these are typically based on single dimensions (e. g. financial or technology aspects). This paper proposes a multidimensional decision support framework, based on the Balanced Scorecard concept. The presented approach introduces four perspectives and a related set of initial decision parameters to support decision making. The perspectives are (a) financial/monetary, (b) business processes, (c) supporting processes and (ICT) infrastructure and (d) information security, risks and compliance. Perspectives and adaptable sets of decision parameters also may serve as foundation for software-based decision support instruments.