Adaptive Diagnosis for Fault Tolerant Data Fusion Based on α-Rényi Divergence Strategy for Vehicle Localization

When applying a diagnostic technique to complex systems, whose dynamics, constraints, and environment evolve over time, being able to re-evaluate the residuals that are capable of detecting defaults and proposing the most appropriate ones can quickly prove to make sense. For this purpose, the concept of adaptive diagnosis is introduced. In this work, the contributions of information theory are investigated in order to propose a Fault-Tolerant multi-sensor data fusion framework. This work is part of studies proposing an architecture combining a stochastic filter for state estimation with a diagnostic layer with the aim of proposing a safe and accurate state estimation from potentially inconsistent or erroneous sensors measurements. From the design of the residuals, using α-Rényi Divergence (α-RD), to the optimization of the decision threshold, through the establishment of a function that is dedicated to the choice of α at each moment, we detail each step of the proposed automated decision-support framework. We also dwell on: (1) the consequences of the degree of freedom provided by this α parameter and on (2) the application-dictated policy to design the α tuning function playing on the overall performance of the system (detection rate, false alarms, and missed detection rates). Finally, we present a real application case on which this framework has been tested. The problem of multi-sensor localization, integrating sensors whose operating range is variable according to the environment crossed, is a case study to illustrate the contributions of such an approach and show the performance.     

Correlation between thermal and rheological studies to characterize the behavior of bitumen

The objective of this work is a comprehensive thermo-rheological study of pure bitumen. The bitumen is a complex material consisting of asphaltenes dispersed in a maltene matrix. As a consequence, its flow behavior is characterized by the presence of a yield stress, which depends on temperature below 50°C. Applying the Cox–Merz rule, a master curve of viscosity can be obtained over a wide range of shear rates for temperatures above 50°C. It can be accurately modeled by a Carreau–Yasuda law with a yield stress. This specific rheological behavior can be explained by the changes induced by the temperature on the microstructure, evidenced by modulated differential scanning calorimetry measurements.     

Thermoelectric Properties of High-Entropy Wolframite Oxide: (CoCuNiFeZn)1−xGaxWO4

Herein, the synthesis of high-entropy wolframite oxide (CoCuNiFeZn)_1-xGaxWO₄ through standard solid-state route followed by spark plasma sintering and their structural, microstructural, and thermoelectric (TE) properties are investigated. X-ray diffraction pattern followed by patterns matching refinement shows a monoclinic structure with the volume of the unit cell decreasing with increasing Ga content. The optical bandgap for these oxides shows a cocktail effect in high-entropy configuration. The Seebeck coefficient indicates electrons as dominating charge carriers with a nondegenerate behavior. The electrical resistivity decreases with increasing temperature depicting a semiconducting nature. Thermal conductivity in high-entropy samples (κ ≈ 2.1 W m⁻¹ K⁻¹ @ 300 K) is significantly lower as compared to MgWO₄ (κ ≈ 11.5 W m⁻¹ K⁻¹ @ 300 K), which can be explained by the strong phonon scattering due to large lattice disorder in high-entropy configuration. The TE figure of merit zT increases with Ga doping via modifying all three TE parameters positively.     

Stereoselective synthesis of enantiopure N-protected-3-arylpiperazines from keto-esters

An efficient method for a stereoselective synthesis of optically pure N-Boc-3-arylpiperazines has been developed. After optimization of the protecting group strategy and experimental conditions, compounds were obtained via a highly stereoselective synthesis in up to 45% overall yield. This is a practical route to optically pure piperazines for medicinal chemistry.     

Structure,dielectric and optical properties of p-type (PVA/CuI) nanocomposite polymer electrolyte for photovoltaic cells

A novel PVA/CuI nanocomposite polymer electrolyte layer synthesized via the reduction of CuCl₂ by NaI in an aqueous PVA solution. The as-prepared films were characterized by X-ray diffraction, scanning electron microscope, as well as impedance spectroscopy. The obtained results indicated the formation of hexagonal CuI nano particles of ≈55 nm sizes embedded in the PVA matrix. In addition, the study of dielectric parameters and conductivity of PVA/CuI nanocomposite in wide range of temperature and frequency are given and discussed. The frequency dependence of ac-conductivity suggests power law with an exponent 0.026 < s < 0.73 which predicts hopping of charge carriers. The bulk conductivity showed activation with temperature, significant values of activation energy are deduced and discussed. An average value of the energy gap width, 2.05 eV obtained using optical absorption in UV–visible spectra for PVA/CuI nanocomposite polymer electrolyte.     

Azabicyclo[3.1.0]hexane-1-ols as frameworks for the asymmetric synthesis of biologically active compounds

Azabicyclo[3.1.0]hexane-1-ols, easily obtained by Ti(IV)-mediated cyclopropanation of amino acid derivatives, constitute versatile, and unprecedented intermediates for the asymmetric synthesis of pharmacologically active products. Indeed, through selective rearrangement, these compounds undergo unusual ring cleavage to lead to pyrrolidinones. Fe(III)-promoted ring opening followed by basic dehydrohalogenation furnishes optically active dihydropyridinones, while Ce(IV)-promoted ring opening provides chiral tricyclopiperidinones via a radical process.     

Water-based conditions for the microscale parallel synthesis of bicyclic lactams

We report efficient miniaturized conditions to prepare arrays of bicyclic lactams for screening. The nature of the solvent is usually an important factor of reactivity. At a small synthesis scale, when automated pipetting devices are required, physical properties of the solvent, such as surface tension and vapor pressure also become very important. After having shown that a complete evaporation of a solution of reagents in water or a mixture of ethanol and water yields the expected lactams, we exemplified the reaction and procedure with the preparation of a library of 80 members. Our synthesis scheme is validated for synthesis scales from 1 to 100 mg. Therefore, it can be used both to produce rapidly test samples for HTS as well as to prepare intermediates for the synthesis of more elaborated nature-inspired compounds.     

Segmental motions of poly(ethylene glycol) chains adsorbed on Laponite platelets in clay-based hydrogels: a NMR investigation

The segmental dynamics of poly(ethylene glycol) (PEG) chains adsorbed on the clay platelets within nanocomposite PEG/Laponite hydrogels was investigated over the tens of microseconds time scale, using combined solution and solid-state NMR approaches. In a first step, the time evolution of the molecular mobility displayed by the PEG chains following the addition to a Laponite aqueous dispersion was monitored during the aggregation of the clay disks and the hydrogel formation, by means of (1)H solution-state NMR. Part of the PEG repeat units were found to get strongly constrained during the gelation process. Comparisons between this time evolution of the PEG local dynamics in the PEG/Laponite/water systems and the increase of the macroscopic storage shear modulus, mainly governed by the assembling of the Laponite disks, indicate that the slowing down of the segmental motions arises from adsorbed PEG repeat units or chain portions strongly constrained between aggregated clay layers. In a second step, after completion of the gelation process, the molecular motions of the adsorbed PEG chains were probed by (1)H solid-state NMR spectroscopy. (1)H double-quantum experiments indicate that the adsorbed PEG repeat units, though reported to be frozen over a few tens of nanoseconds, still display significant reorientational motions over the tens of microseconds time scale. Using a comparison with a model system of amorphized PEG chains, the characteristic frequency of these segmental motions was found to range between 78.0 kHz and 100.7 MHz at 300 K. Interestingly, at this temperature, the level of reorientational motions detected for these adsorbed PEG chain portions was found to be as restricted as the one of bulk amorphous PEG chains, cooled at a slightly lower temperature (about 290 K).     

Synthesis and Characterizations of Keplerate Nanocapsules Incorporating L- and D-Tartrate Ligands

Five new tartrate-containing Keplerate compounds have been synthesized and characterized in the solid state and in solution. These characterizations evidenced the total replacement of inner sulfate ligands by L- or D-tartrate ligands in aqueous medium under heating during several days. To our knowledge these compounds correspond to the first Keplerate molecules incorporating chiral ligands. The ¹H NMR studies supported by X-ray crystallographic analysis are consistent with the coordination of 24–30 tartrates within the Mo₁₃₂ capsule which are located in close vicinity. The NMR signals of the encapsulated ligands appear particularly broad which precludes the use of advanced NMR methodologies but the solid state NMR provided further characterization of ligand substitution within the capsule by carboxylates. To our knowledge it is the first time that a solid state NMR study of a Keplerate is reported in the literature.