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To improve the indoor positioning accuracy, the methods of position fingerprint and pedestrian dead reckoning (PDR) are used to study the indoor positioning algorithm.For position fingerprint algorithm, the fingerprint database is optimized through the offline data training phase, and the optimization of the nearest neighbor algorithm is carried out by limiting the region weighted value K through the online real-time matching phase.For PDR algorithm, the self-adaptation peak detection algorithm used for step frequency detection is proposed.The improved nonlinear model is used for step size estimation.Moreover, The gyroscope's information are fused to magnetometer's information in the heading estimation.Finally, the unscented Kalman filter is used to fuse the position fingerprint algorithm and PDR method, which improves the positioning accuracy and the practicability of the fusion algorithm is verified by the positioning system.

The pursuit of operational advancements in direct formic acid fuel cells (DFAFCs) necessitates the development of high-performance platinum (Pt)-based catalysts for formic acid electrooxidation (FAOR). However, FAOR on Pt-based catalysts follows a dual pathway mechanism, in which the direct pathway is a preferred route due to its efficient dehydrogenation process. Conversely, the indirect pathway results in the generation of adsorbed CO species, a process that deleteriously poisons the active sites of the catalyst, with CO species only being oxidizable at higher potentials, causing a significant compromise in catalyst performance. Herein, we have successfully synthesized Pt-C3N4@CNT, where three Pt clusters are precisely dispersed in a triplet form within the C3N4 by virtue of the unique structure of C3N4. The mass activity for the direct pathway (0.44 V) delivered a current density of 1.91 A mg Pt − 1 , while the indirect pathway (0.86 V) had no obvious oxidation peak. The selectivity of Pt-C3N4@CNT catalysts for the direct pathway of FAOR was improved due to the special structure of C3N4, which facilitates the dispersion of Pt tri-atoms in the structure and the electronic interaction with Pt. In this study, we provide a new strategy for the development of highly active and selective catalysts for DFAFCs. [ABSTRACT FROM AUTHOR]

An equation of state (EOS) explicit in Helmholtz free energy has been improved to calculate the PVTx and vapor–liquid phase equilibrium properties of CH 4 –CO 2 fluid mixture. This EOS, where four mixing parameters are used, is based on highly accurate EOSs recommended by NIST for pure components (CH 4 and CO 2 ) and contains a simple generalized departure function presented by Lemmon and Jacobsen (1999). Comparison with experimental data available indicates that the EOS can calculate both vapor–liquid phase equilibrium and volumetric properties of this binary fluid system with accuracy close to that of experimental data up to high temperature and pressure within full range of composition. The EOS of CH 4 –CO 2 fluid, together with the updated Gibbs free energy model of solid CO 2 (dry ice), is applied to calculate the CH 4 content ( x CH4 ) and molar volume ( V m ) of the CH 4 –CO 2 fluid inclusion based on the assumption that the volume of an inclusion keeps constant during heating and cooling. V m − x CH 4 diagrams are presented, which describe phase transitions involving vapor, liquid and CO 2 solid phases of CH 4 –CO 2 fluid inclusions. Isochores of CH 4 –CO 2 inclusions at given x CH 4 and V m can be easily calculated from the improved EOS. [ABSTRACT FROM AUTHOR]

Abstract: This work reports the application of thermodynamic models, including equations of state, to binary (salt-free) CH4–H2O fluid inclusions. A general method is presented to calculate the compositions of CH4–H2O inclusions using the phase volume fractions and dissolution temperatures of CH4 hydrate. To calculate the homogenization pressures and isolines of the CH4–H2O inclusions, an improved activity–fugacity model is developed to predict the vapor–liquid phase equilibrium. The phase equilibrium model can predict methane solubility in the liquid phase and water content in the vapor phase from 273 to 623K and from 1 to 1000bar (up to 2000bar for the liquid phase), within or close to experimental uncertainties. Compared to reliable experimental phase equilibrium data, the average deviation of the water content in the vapor phase and methane solubility in the liquid phase is 4.29% and 3.63%, respectively. In the near-critical region, the predicted composition deviations increase to over 10%. The vapor–liquid phase equilibrium model together with the updated volumetric model of homogenous (single-phase) CH4–H2O fluid mixtures (Mao S., Duan Z., Hu J. and Zhang D. (2010) A model for single-phase PVTx properties of CO2–CH4–C2H6–N2–H2O–NaCl fluid mixtures from 273 to 1273K and from 1 to 5000bar. Chem. Geol. 275, 148–160), is applied to calculate the isolines, homogenization pressures, homogenization volumes, and isochores at specified homogenization temperatures and compositions. Online calculation is on the website: http://www.geochem-model.org/. [Copyright &y& Elsevier]

The electrocatalytic conversion of formate in alkaline solutions is of paramount significance in the realm of fuel cell applications. Nonetheless, the adsorptive affinity of adsorbed hydrogen (H ad ) on the catalyst surface has traditionally impeded the catalytic efficiency of formate in such alkaline environments. To circumvent this challenge, our approach introduces an interfacial push-pull effect on the catalyst surface. This mechanism involves two primary actions: First, the anchoring of palladium (Pd) nanoparticles on a phosphorus-doped TiO 2 substrate (Pd/TiO 2 -P) promotes the formation of electron-rich Pd with a downshifted d band center, thereby "pushing" the desorption of H ad from the Pd active sites. Second, the TiO 2 -P support diminishes the energy barrier for H ad transfer from the Pd sites to the support itself, "pulling" H ad to effectively relocate from the Pd active sites to the support. The resultant Pd/TiO 2 -P catalyst showcases a remarkable mass activity of 4.38 A mg Pd -1 and outperforms the Pd/TiO 2 catalyst (2.39 A mg Pd -1 ) by a factor of 1.83. This advancement not only surmounts a critical barrier in catalysis but also delineates a scalable pathway to bolster the efficacy of Pd-based catalysts in alkaline media.

This study addresses the critical challenge in alkaline direct formate fuel cells (DFFCs) of slow formate oxidation reaction (FOR) kinetics as a result of strong hydrogen intermediate (H ad ) adsorption on Pd catalysts. We developed WO 3 -supported Pd nanoparticles (EG-Pd/WO 3 ) via an organic reduction method using ethylene glycol (EG), aiming to modulate the d-band center of Pd and alter H ad adsorption dynamics. Cyclic voltammetry demonstrated significantly improved H ad desorption kinetics in EG-Pd/WO 3 catalysts. Density functional theory (DFT) calculations revealed that the presence of EG reduces the d-band center of Pd, leading to weaker Pd-H bonds and enhanced H ad desorption during the FOR. This research provides a new approach to optimize catalyst efficiency in DFFCs, highlighting the potential for more effective and sustainable energy solutions through advanced material engineering.