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31.
《Comptes Rendus Physique》2019,20(3):218-227
In the automotive domain, Cooperative Localization (CLoc) is a new promising paradigm that aims at outperforming conventional Global Navigation Satellite Systems (GNSS) in terms of positioning accuracy, robustness, and service continuity, by relying on Vehicle-to-Vehicle (V2V) communications and hybrid data fusion. However, the growing number and the variety of the sensors aboard vehicles raise unprecedented challenges, especially in the context of distributed fusion approaches. This paper thus compares parametric and nonparametric Bayesian data fusion engines (e.g., based on cooperative variants of the Extended Kalman Filter (EKF) and Particle Filter (PF), respectively), while validating a CLoc scheme suitable to Vehicular Ad Hoc Networks (VANETs). More particularly, absolute position information from both onboard GNSS receiver and ITS-G5 V2V messages, as well as relative distance measurements based on the Impulse Radio–Ultra-Wideband (IR–UWB) technology, are combined into a single location solution that is hopefully more robust and more accurate than that of standalone GNSS. First, we investigate V2V ranging accuracy on a highway under real mobility conditions. In the same environment, we then provide offline validations of CLoc positioning, confirming significant performance gains through cooperation over conventional GNSS, even in case of poor initialization. In this specific context, the PF solution is thus shown to yield even better accuracy in comparison with EKF, thanks to its fine robustness against faced non-linear dynamics and non-Gaussian noise processes. Finally, we illustrate the resilience of the proposed solution under temporary GNSS denial.  相似文献   
32.
The Morse–Witten theory provides a formulation for the inter-bubble forces and corresponding deformations in a liquid foam, accurate in the limit of high liquid fraction. Here we show how the theory may be applied in practice, including allowing for polydispersity in the bubble sizes. The resulting equilibrated 2D structures are consistent with direct calculations, within the limitations of the theory. The path to developing a 3D model is outlined for future work.  相似文献   
33.
In this paper, we report the studies of the solution structures of synthetic pentadeoxyribonucleotide d-TGGGT(NH4 + salt) using 2D–NMR. The 1H–NMR experiments with different temperatures and concentrations reveal an equilibrium between single strand and aggregation. In the experimental condition(22°C, 13mmol/ L), the cross peaks in the COSY spectrum are mainly from single strand, and the spin systems of sugar resonances of this component can be assigned. In contrast, the cross peaks in the NOESY spectrum mainly come from aggregation and the sequential assignments of bases, sugar 1′, 2′ and 2″ protons can be carried out. From NOE connectivities, it is obvious that the aggregation adopts a right–handed helix conformation. It is suggested that the aggregation in our experiment corresponds to the tetramolecular complex.  相似文献   
34.
The current study was conducted to investigate the convective heat transfer coefficient of a novel TiO2–CNT hybrid nanofluid through the shell-and-tube heat exchanger under a laminar flow and the effects of temperature and mass fraction on it. TiO2–CNT hybrid nanofluids were prepared using a new and modified hydrolysis technique. The thermal conductivity of the TiO2–CNT hybrid nanofluid and other thermo-physical properties were assessed. Results indicate that the effective thermal conductivity and heat transfer coefficient of the base fluid was influenced significantly and increased by the 0.2 wt% of this novel hybrid nanofluid in distilled water.  相似文献   
35.
A new variant of the method of finding the equation of state in the Mie–Grüneisen form is presented. It is based only on high-pressure isotherms of solids. Using this procedure, the semiempirical equation of state and shock adiabats of solids may be found at high pressures and high temperatures. The method is tested on periclase MgO within the range of shock pressures up to 300–500 GPa.  相似文献   
36.
Pressure-dependent thermodynamic properties of the ambient and high pressure phases of aluminum nitride (w-AlN and rs-AlN) were calculated from first principles in order to determine their phase boundary in the p? T phase diagram. These predictions were checked by static HP/HT experiments, using a multianvil press and an Al/N/H precursor with low decomposition temperature as educt. The experimental data show that at temperatures between 1000 and 2000 K, the boundary line between the two phases is situated between 11 and 12 GPa, which is ~1.3 GPa lower than the theoretical result and generally lower than previously assumed. The hardness of rs-AlN – measured for the first time – is ~30 GPa (Knoop indenter at loads of 25–50 g), twice as hard as w-AlN. Shock wave recovery experiments on nano w-AlN allowed testing of the chemical and thermal stability of rs-AlN, and determination of its infrared absorption and 27Al NMR data. The shock wave technique will eventually enable the synthesis of larger amounts of rs-AlN, making it available for technological use. Finally, implications on the high pressure stability of phases in the Si–Al–O–N system are discussed in the light of thermoelastic properties of AlN.  相似文献   
37.
Y.Z. Chen  X.Y. Lin  X.Z. Wang 《哲学杂志》2013,93(26):2239-2253
A hypersingular integral equation for the curved crack problems of an elastic half-plane is introduced. Formulation of the equation is based on the usage of a modified complex potential. The potential is generally expressed in the form of a Cauchy-type integral. The modified complex potential is composed of the principal part and the complementary part. The principal part of the complex potential is actually equivalent to the original complex potential for the curved crack in an infinite plate. The role of the complementary part is to eliminate the boundary traction along the boundary of the half-plane caused by the principal part. From the assumed boundary traction condition, a hypersingular integral equation is obtained for the curved crack problems of an elastic half-plane. The curve length coordinate method is used to obtain a final solution. Several numerical examples are presented that prove the efficiency of the suggested method.  相似文献   
38.
The influence of substitutionally dissolved Al in ferritic Fe–4.75 at.% Al alloy on the nucleation and growth of γ′ iron nitride (Fe4N1? x ) was investigated upon nitriding in NH3/H2 gas mixtures. The nitrided specimens were characterised employing optical microscopy, scanning electron microscopy, transmission electron microscopy, electron probe microanalysis and X-ray diffraction. As compared to the nitriding of pure ferrite (α-Fe), where a layer of γ′ develops at the surface, upon nitriding ferritic Fe–4.75 at.% Al an unusual morphology of γ′ plates develops at the surface, which plates deeply penetrate the substrate. In the diffusion zone, nano-sized precipitates of γ′ and of metastable, cubic (NaCl-type) AlN occur, having, with the ferrite matrix, a Nishiyama–Wassermann orientation relationship and a Bain orientation relationship, respectively. The γ′ plates contain a high density of stacking faults and fine ε iron nitride (Fe2N1? z ) precipitates, although the formation of ε iron nitride is not expected for the employed nitriding parameters. On the basis of dedicated nitriding experiments it is shown that the unusual microstructural development is a consequence of the negligible solubility of Al in γ′ and the obstructed precipitation of the thermodynamically stable, hexagonal (wurtzite-type) AlN in ferrite.  相似文献   
39.
40.
Shibayan Roy 《哲学杂志》2013,93(5):447-463
Deformation instabilities, such as shear cracking and grain boundary cavitation, which are observed in the secondary tensile region of Ti–6Al–4V alloy during compressive deformation in the (α?+?β)-phase field, do not form in Ti–6Al–4V–0.1B alloy when processed under the same conditions. This has been attributed to the microstructural modifications, e.g. the absence of grain boundary α and adjacent grain boundary retained β layers and a lower proportion of 90o-misoriented α-colonies that occur with boron addition.  相似文献   
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