Some remarks on Kalman filters for the multisensor fusion

Multisensor data fusion has found widespread application in industry and commerce. The purpose of data fusion is to produce an improved model or estimate of a system from a set of independent data sources. There are various multisensor data fusion approaches, of which Kalman filtering is one of the most significant. Methods for Kalman filter based data fusion includes measurement fusion and state fusion. This paper gives first a simple a review of both measurement fusion and state fusion, and secondly proposes two new methods of state fusion based on fusion procedures at the prediction and update level, respectively, of the Kalman filter. The theoretical derivation for these algorithms are derived. To illustrate their application, a simple example is performed to evaluate the proposed methods and compare their performance with the conventional state fusion method and measurement fusion methods.     

Montmorillonite-hybridized g-C3N4 composite modified by NiCoP cocatalyst for efficient visible-light-driven photocatalytic hydrogen evolution by dye-sensitization

The photocatalytic hydrogen evolution performance of g-C₃N₄ was enhanced via the hybridization with montmorillonite (MMT) and using NiCoP as cocatalyst. The highest hydrogen-evolution rate from water splitting under visible-light irradiation observed over MMT/g-C₃N₄/15%NiCoP was 12.50 mmol g⁻¹ h⁻¹ under 1.0 mmol L⁻¹ of Eosin Y-sensitization at pH of 11, which was ∼26.0 and 1.6 times higher than that of MMT/g-C₃N₄ (0.48 mmol g⁻¹ h⁻¹) and g-C₃N₄/15%NiCoP (7.69 mmol g⁻¹ h⁻¹). The apparent quantum yield at 420 nm reached 40.3%. The remarkably improved photocatalytic activity can be ascribed to the increased dispersion of g-C₃N₄ layers, staggered conduction band potentials between g-C₃N₄ and NiCoP, as well as the electrostatic repulsion originated from negatively charged MMT. This work demonstrates that MMT can be an outstanding support for the deposition of catalytically active components for photocatalytic hydrogen production.     

Surface structural alteration of multi-walled carbon nanotubes decorated by nickel nanoparticles based on laser ablation/chemical reduction methods to enhance hydrogen storage properties

The catalytic effect of nickel is addressed to decorate the multi-walled carbon nanotubes for the purpose of hydrogen storage. The hydrogen sorption/desorption are investigated using the volumetric technique. Nickel nanoparticles are distributed on the surface of nanotubes using the laser ablation/chemical reduction treatments. The hydrogen uptake is elevated at higher nickel population up to a certain value and then experiences a significant drop for larger nickel content. The laser treatment is accompanied by the induced pores around nanotubes. This gives rise to the creation of the larger pores at higher laser doses leading to decrease the hydrogen trapping. Despite the pore size distribution strongly alters during both synthesis methods, however the abundance of small pore size in laser treatments is relatively higher than the that of the other technique. In comparison, the laser ablation demonstrates a relatively smaller desorption temperature against chemical one, mainly owing to the formation of larger pore size/volume. Generally, the hydrogen trapping efficiently takes place in the laser treated samples against chemical reduction method. The highest value of hydrogen storage ∼1% (0.6% weight) is corresponding to 12.3% (13% weight) of nickel loading via the laser ablation (chemical reduction).     

Study on the gaseous and electrochemical hydrogen storage properties of as-milled CeMgNi-based alloys

For gaining further insight into the involvement of the gaseous and electrochemical hydrogen storage properties of CeMg₁₂-type alloys, partial substitution and ball milling were both used to synthesize the nanocrystalline and amorphous CeMg₁₁Ni + x wt.% Ni (x = 100, 200) samples. This research aims at elucidating the functional roles of Ni content and milling time on samples' structure and hydrogen storage performance. X-Ray diffraction and high-resolution transmission electron microscope were used to reveal the micro constructions of alloys. To determine the gaseous hydrogen storage property, Sievert's apparatus and a thermal gravity analysis bonded with a H₂ probe were adopted. The dehydrogenation activation energy was computed in the Kissinger method. The electrochemical performances of the as-milled samples were measured through a constant current system. Further researches showed that the electrochemical performance of as-milled samples had been dramatically improved by increasing Ni content. With milling duration lengthens, the gaseous hydrogen absorption capacity, gaseous hydriding rate and high rate discharge capability of samples reached the maximal values, but electrochemical discharge capacity and gaseous dehydriding rate always increased. The dehydrogenation activation energy decrease resulted by improving Ni percent and milling duration was deemed as the cause of the excellent gaseous kinetics of samples.     

Energetic and exergetic analyses of a combined system consisting of a high-temperature polymer electrolyte membrane fuel cell and a thermoelectric generator with Thomson effect

A combined system model consisting of a high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC), a regenerator and a thermoelectric generator (TEG) is proposed, where the TEG is applied to harness the generated waste heat in the HT-PEMFC for extra electricity production. The TEG considers not only the Seebeck effect and Peltier effect but also the Thomson effect. The mathematical expressions of power output, energy efficiency, exergy destruction rate and exergy efficiency for the proposed system are derived. The energetic and exergetic performance characteristics for the whole system are revealed. The optimum operating ranges for some key performance parameters of the combined system are determined using the maximum power density as the objective function. The combined system maximum power density and its corresponding energy efficiency and exergy efficiency allow 19.1%, 12.4% and 12.6% higher than that of a stand-alone HT-PEMFC, while the exergy destruction rate density is only increased by 8.6%. The system performances are compared between the TEG with and without the Thomson effect. Moreover, the impacts of comprehensive parameters on the system performance characteristics are discussed. The obtained results are helpful in developing and designing such an actual combined system for efficient and clean power production.     

Gas hydrogen absorption and electrochemical properties of Mg24Ni10Cu2 alloys improved by Y substitution,ball milling and Ni addition

Mg₂₄Ni₁₀Cu₂ and Mg₂₂Y₂Ni₁₀Cu₂ alloys were prepared via vacuum induction melting, and the nanocrystalline/amorphous Mg₂₄Ni₁₀Cu₂ and Mg₂₄Ni₁₀Cu₂ + 100 wt% Ni alloys were synthesized through ball milling method. Microstructure and hydrogen storage properties of the alloys were investigated and compared as well. The results suggest that adding Ni in the milling process significantly promotes formation of amorphous and nanocrystalline structure. For these four alloys, the as-milled Mg₂₄Ni₁₀Cu₂ with 100 wt% Ni shows the best hydrogen storage performances that 2.03 wt% hydrogen content can be absorbed just in 1 min, and the electrochemical capacity reaches to 899.2 mAh/g. Furthermore, ball milling with Ni promotes the charge transfer reaction and hydrogen diffusion ability which is advantageous to the high rate discharge ability.     

Facile synthesis of uniform LaSrCoO4 using amino acid-derived surfactant and its utilization as an excellent cathode material for intermediate temperature solid oxide fuel cell

In this paper, a uniform and defective LaSrCoO₄ was prepared by using amino acid derived surfactant (N-(2-hydroxylalkyl)-l-Phenylalanine). Owing to rich active groups of N-(2-hydroxylalkyl)-l-Phenylalanine, the resultant LaSrCoO₄ showed enhanced specific surface area and good electro-catalytic property. The porous K₂NiF₄-type LaSrCoO₄ was verified as a good cathode material for intermediate temperature solid oxide fuel cells (SOFCs). The LaSrCoO₄ electrode demonstrated good electrochemical performance, including good electrical conductivity (138.7 S cm⁻¹, in air at 800 °C), low polarization resistance R_p (0.108 Ω cm², symmetric cells in air at 800 °C) and high power densities (688 mW cm⁻² at 800 °C). The as-prepared LaSrCoO₄ shows a promising application as the cathode materials in the intermediate temperature SOFCs.     

Synergistic effect of {101} crystal facet and bulk/surface oxygen vacancy ratio on the photocatalytic hydrogen production of TiO2

Anatase titanium dioxide (TiO₂) nanocrystals with different percentages (up to 95%) of exposed {101} facet and different concentration ratios of bulk single-electron-trapped oxygen vacancies (SETOVs) to surface oxygen vacancies (SOVs) were prepared by alcohol-thermal method with nanotube titanic acid as the precursor in combination with solid-state reduction by NaBH₄. The as-prepared TiO₂ nanocrystals were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, electron spin resonance spectroscopy, and ultraviolet–visible light spectrometry. The effects of the percentage of crystal facets and the concentration ratio of bulk SETOVs/SOVs on the photocatalytic hydrogen production rate of TiO₂ nanocrystals were investigated with positron annihilation lifetime spectroscopy as well as photocurrent test. Findings indicate that the percentage of the exposed {101} facets of the as-prepared TiO₂ nanocrystals and their concentration ratios of bulk SETOVs/SOVs can be well tuned by properly adjusting the amount of NaBH₄ and the reduction reaction time as well. Increasing percentage of the {101} facet of anatase TiO₂ nanocrystals contributes to improving their photocatalytic hydrogen production activity, because the {101} facets of the anatase TiO₂ nanocrystals possess enriched electrons and can act as the reduction sites to enhance the reduction reaction of H⁺ affording H₂ in the sacrifice system of splitting water. Both the bulk SETOVs and SOVs contribute to the improvement of the light absorption while SOVs can facilitate the separation of photogenerated charges, thereby adding to the photocatalytic activity. However, the bulk SETOVs and excessive SOVs are also the combination centers of photogenerated charges, which means it is essential to maintain a suitable concentration ratio of the bulk SETOVs/SOVs so as to enhance the light absorption and achieve the best separation efficiency of photogenerated charges and achieve the best photocatalytic activity for hydrogen production. Particularly, when anatase TiO₂ nanocrystal with a high percentage (95%) of exposed {101} facet is reduced by NaBH₄ at a mass ratio of 2: 1 for 20 min, the resultant reduced H-TiO₂ nanocrystal (denoted as H-TiO₂-R20(2:1)) provides the highest photocatalytic hydrogen productive rate. Furthermore, the combination of 0.5% Pt/H-TiO₂-R20(2:1) with 0.5% Pt/WO₃ can split water to simultaneously produce H₂ and O₂, showing promising potential for splitting water affording hydrogen and oxygen.     

Separation of hot electrons and holes in Au/LaFeO3 to boost the photocatalytic activities both for water reduction and oxidation

Construction of plasmon-based nanostructures is an effective way to enhance the photocatalytic activities of semiconductor photocatalysts for water-splitting. However, the synergistic effect of plasmon-related hot electrons and holes for water splitting in the plasmon-hybrid photocatalyst is rarely considered. Herein, we construct a plasmon-based Au/LaFeO₃ composite photocatalyst to investigate the complex roles of hot electrons and holes for solar water splitting. Benefiting from the formation of Schottky junction and surface plasmon resonance effect of the Au nanoparticles, the synthesized photocatalyst exhibits an excellent photocatalytic activity for each half-reaction of water splitting, and the rates for H₂ and O₂ generation are obtained as high as 202 μmol g⁻¹ h⁻¹ and 23 μmol g⁻¹ h⁻¹, respectively. Moreover, an in-depth investigation reveals that the improved hydrogen evolution is caused by the hot electron injection from Au to LaFeO₃, and the hot holes in Au induced by the separation of hot charges can initiate the water oxidation directly on the surface of gold. Thus, this work provides a new insight into the synergistic effect of plasmon-related hot electrons and holes for boosting the photocatalytic reactions.     

Hydrogen and energy savings using heuristic allocation of mass exchangers in process synthesis: Technical analysis

For our works, Mass Exchangers (MEs) are membrane equipment that exchange some component between two streams in a countercurrent arrangement. In previous works these were proposed to use them (with the goal of hydrogen recovery, energy saving and waste minimization) at different stages of the hierarchical decision procedure for process synthesis by Douglas: at an early design stage, when deciding the recycle structure of the process (resulting in considerable changes in the process structure); or at a final design stage, before deciding the mass and energy integrations of process streams (resulting in minor changes in the process structure).The heuristic allocation of MEs was used independently at both design stages in previous works, with the goal of comparing with other design alternatives reported in the literature that use membranes in the conventional configuration (one feed stream and two exit streams; retentate and permeate). In contrast, the present work compares the results of using MEs, when they are used individually at both design stages, and when they are used jointly at both design stages, in different configurations. For the case study example (the HDA Process), the use of a ME at an early design stage reduces the fresh hydrogen consumed by 3.37%, and the recycle compressor power by 4.09%. The use of a ME at a final design stage reduces the fresh hydrogen consumed by 31.64%, but it does not reduce the recycle compressor power. The joint use of the MEs at both design stages reduces the fresh hydrogen consumed by 14.54%, and the recycle compressor power by 2.91%.The joint use of MEs at both design stages retains the principal benefits of its use at early and final design stages (energy saving and hydrogen recovery, principally), so when both a reduction in the fresh hydrogen consumed and in the recycle compressor power is desired, it is the most appropriate option.