Coordinated Risk Mitigation Strategy for Integrated Energy Systems under Cyber-Attacks

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Efficient Estimation of Stochastic Parameters: A GLS Approach

This thesis presents a novel rolling GLS-based model to improve the precision of time-varying parameter estimates in dynamic linear models. Through rigorous simulations, the rolling GLS model exhibits enhanced accuracy in scenarios with smaller sample sizes and maintains its efficacy when the normality assumption is relaxed, distinguishing it from traditional models like Kalman Filters. Furthermore, the thesis expands on the model to tackle more complex stochastic structures and validates its effectiveness through practical applications to real-world financial data, like inflation risk premium estimations. The research culminates in offering a robust tool for financial econometrics, enhancing the reliability of financial analyses and predictions

Impact de la nanostructuration sur la diffusion de l’hydrogène étudiée par une approche multi-échelle dans le matériau pyrochlore La₂Zr₂O₇ dopé Sr

Due to the increase of energy demand and environmental issues of fossil energy, many researches are moving towards green energy. In this context, several technologies using hydrogen have been developed. To reduce the working temperature of SOFC fuel cell, the concept of PCFC is emerging. The ionic conductivity is due to hydrogen instead of oxide anions. The A₂B₂O₇ compounds are promising candidates as electrolyte materials for PCFC. However, it appears necessary to understand the hydrogen diffusion mechanisms in these materials before to investigate news materials with best properties. In this work, a multi-scale approach is performed to study the impact of microstructure on proton-conducting properties in Sr doped La₂Zr₂O₇ as model material. Several synthetic routes have been used to obtain powders with different morphologies.At the nanometric scale, studies by X-ray diffraction, then by Raman spectroscopy and electron energy loss spectroscopy (EELS) have shown that the low temperature structure were disordered a pyrochlore structure. The latter is ordered during thermal annealing. At the micrometric scale, ion beam techniques allowed us to get the hydrogen concentration profiles on the previously hydrated materials. The amount of incorporated hydrogen depends on the densification processes. At the macroscopic scale, impedance spectroscopy measurements were used to obtain information on the electrical behavior of materials. Evidence of proton conductivity has been demonstrated in wet atmosphere. This conductivity is highly dependent not only on the sample preparation but also on processes densification used.Face aux demandes croissantes en énergie, la tendance mondiale est au développement des énergies non émettrices de gaz à effets de serre. Dans ce contexte, plusieurs technologies de piles à combustibles utilisant l’hydrogène ont été développées. Le souhait d’abaisser les températures de fonctionnement des SOFC a conduit à s’intéresser au concept des piles PCFC dont la conduction ionique de l’électrolyte est assurée par l’hydrogène au lieu des anions oxydes. Les composés pyrochlores A₂B₂O₇ sont des candidats prometteurs comme matériaux d’électrolyte de PCFC.Il s’avère toutefois indispensable de comprendre les mécanismes de diffusion de l’hydrogène dans ces matériaux avant d’orienter les recherches vers la mise au point d’un matériau électrolyte performant. Dans ce travail, une approche multi-échelle est employée pour étudier l’impact de microstructure sur les propriétés de conduction protonique du matériau modèle La₂Zr₂O₇ dopé Sr. Pour ce faire, plusieurs voies de synthèse ont été utilisées afin d’obtenir des morphologies de poudres différentes.A l’échelle nanométrique, les études structurales menées par diffraction des rayons X puis des études par spectroscopie Raman et spectroscopie de pertes d’énergie des électrons (EELS) ont montré que la structure basse température étaient une structure pyrochlore désordonnée. Cette dernière s’ordonne lors de recuit thermique.Les techniques d’analyses par faisceau d’ions ont permis de sonder à l’échelle micrométrique les profils de concentration en hydrogène des matériaux préalablement hydratés. La quantité d’hydrogène incorporé dépend de la densification de la pastille.Les mesures par spectroscopie d’impédance ont permis d’obtenir des informations à l’échelle macroscopique du comportement électrique des matériaux. Une conductivité protonique a été mise en évidence sous atmosphère humide. Cette conductivité est fortement dépendante non seulement de la méthode d’élaboration des matériaux mais aussi des procédés de densification utilisés

Efficient Estimation of Stochastic Parameters: A GLS Approach

This thesis presents a novel rolling GLS-based model to improve the precision of time-varying parameter estimates in dynamic linear models. Through rigorous simulations, the rolling GLS model exhibits enhanced accuracy in scenarios with smaller sample sizes and maintains its efficacy when the normality assumption is relaxed, distinguishing it from traditional models like Kalman Filters. Furthermore, the thesis expands on the model to tackle more complex stochastic structures and validates its effectiveness through practical applications to real-world financial data, like inflation risk premium estimations. The research culminates in offering a robust tool for financial econometrics, enhancing the reliability of financial analyses and predictions

Work orders management based on XML file in printing

The Extensible Markup Language (XML) technology is increasingly used in various field, if it’s used to express the information of work orders will improve efficiency for management and production. According to the features, we introduce the technology of management for work orders and get a XML file through the Document Object Model (DOM) technology in the paper. When we need the information to conduct production, parsing the XML file and save the information in database, this is beneficial to the preserve and modify for information

Eradication of unresectable liver metastasis through induction of tumour specific energy depletion.

Treatment of liver metastasis experiences slow progress owing to the severe side effects. In this study, we demonstrate a strategy capable of eliminating metastatic cancer cells in a selective manner. Nucleus-targeting W18O49 nanoparticles (WONPs) are conjugated to mitochondria-selective mesoporous silica nanoparticles (MSNs) containing photosensitizer (Ce6) through a Cathepsin B-cleavable peptide. In hepatocytes, upon the laser irradiation, the generated singlet oxygen species are consumed by WONPs, in turn leading to the loss of their photothermally heating capacity, thereby sparing hepatocyte from thermal damage induced by the laser illumination. By contrast, in cancer cells, the cleaved peptide linker allows WONPs and MSNs to respectively target nucleus and mitochondria, where the therapeutic powers could be unleashed, both photodynamically and photothermally. This ensures the energy production of cancer cells can be abolished. We further assess the underlying molecular mechanism at both gene and protein levels to better understand the therapeutic outcome

Impact of Spark Plasma Sintering Conditions on Ionic Conductivity in La1.95Sr0.05Zr2O7-δ Electrolyte Material for Intermediate Temperature SOFCs

International audienceSolid Oxide Fuel Cells (SOFC) have attracted much attention as potential energy source. Their high operating temperatures (800°C-1000°C) can lead to thermal, mechanical and chemical problems such as densification of electrodes or formation of an insulating layer at the electrode/electrolyte interface by interdiffusion [1-2]. To overcome these drawbacks, the Proton Ceramic Fuel Cell (PCFC) technology was developed. This technology, where the electrolyte is an H+ ion conductor in the form of ceramic oxide material, exhibits the intrinsic benefits of proton conduction in Polymer Exchange Membrane Fuel Cells (PEMFC) and the advantages of the SOFC technologies. Since the discovery of high temperature protonic conductivity in cerates [3-4], many investigations about pyrochlore-type proton conductors are performed [5-6]. These systems are characterized by mixed valence oxides (often rare earth) and anion vacancies as primary lattice defects. Under wet atmosphere, the proton conduction occurs via the hydration of oxygen vacancies after the material is exposed to a vapour-containing atmosphere according to the following equation 1 (inserted as part of the image file).     The conventional route for the preparation of lanthanum zirconate pyrochlore (LSZO) via solid-state reactions requires multiple milling and high temperature calcination steps. Also, this method leads generally to an heterogeneity of the final product, whereas wet chemical route, which consists of mixing precursors in a solution, could improve compositional homogeneity and stoichiometry. In this work, we have synthesized nano-sized La1,95Sr0,05Zr2O7-d using an oxalic co-precipitation method. As impedance spectroscopy measurements require high densification, only spark plasma sintering (SPS) gives dense materials. Other sintering processes such as hot isostatic pressing induce a segregation of strontium at the surface of the pellet[7],and thereby decrease proton conductivities. LSZO powders were densified using SPS apparatus under different sintering conditions: holding time, temperature and pressure. To maintain the same compacity for different grain sizes, starting powder materials were calcined at different temperatures in order to increase of the particle size. Thus several pellets with either different relative densities or grain sizes were obtained. The grain size increases with increasing of the sintering temperature. The proton conductivity behavior of those pellets was investigated by AC impedance spectroscopy under dry and wet atmospheres. The data were measured in the frequency range 0.1Hz – 6 MHz (Materials mates M2-7260 impedance analyzer) at intermediate temperatures 400-600°C. In order to verify the dependence of total resistance and capacitance, a DC-bias (UDC from 0 to 1V) was applied. The Nyquist diagrams were modeled by equivalent circuits based on resistors and constant phase elements (CPEs).  The ionic conductivities are clearly dependent on grain sizes (see Figure 1). In order to elucidate this dependence, it will be necessary to assess a porosity correction equation. The activation energies, calculated using the Arrhenius equation, increase with increasing grain sizes. The proton conductivities are higher in wet atmosphere than dry atmosphere. For example, the ionic conductivities of 120 nm-LSZO are 2.45 × 10-5 S.cm-1 and 3.30 × 10-5 S.cm-1 under dry and wet atmosphere (5% H2O) at 600°C, respectively. Figure 1 - Nyquist plots of impedance spectra for LSZO with different particle sizes at 600°C References[1]      S.C. Singhal, Solid State Ion. 135 (2000) 305. [2]      C. Xia, W. Rauch, F. Chen, M. Liu, Solid State Ion. 149 (2002) 11. [3]      F. Chen, O.T. Sørensen, G. Meng, D. Peng, J. Mater. Chem. 7 (1997) 481. [4]      H. Iwahara, H. Uchida, K. Ono, K. Ogaki, J. Electrochem. Soc. 135 (1988) 529. [5]      K.E.J. Eurenius, E. Ahlberg, C.S. Knee, Dalton Trans. 40 (2011) 3946. [6]      T. Shimura, M. Komori, H. Iwahara, Solid State Ion. 86–88, Part 1 (1996) 685. [7]      D. Huo, D. Gosset, G. Baldinozzi, D. Siméone, H. Khodja, B. Villeroy, S. Surblé, Solid State Ion. (submitted)

Optimal Borehole Energy Storage Charging Strategy in a Low Carbon Space Heat System

Domestic heating is the major demand of energy systems, which can bring significant uncertainties to system operation and shrink the security margin. From this aspect, the borehole system, as an interseasonal heating storage, can effectively utilize renewable energy to provide heating to ease the adverse impact from domestic heating. This paper proposes an optimal charging strategy for borehole thermal storage by harvesting energy from photovoltaic (PV) generation in a low-carbon space heating system. The system optimizes the heat injection generated by air source heat pump in the charging seasons to charge the borehole, which provides high inlet temperature for ground source heat pump to meet space heating demand in discharging seasons. The borehole is modeled by partial differential equations, solved by the finite-element method at both 2D and 3D for volume simulation. The pattern search optimization is used to resolve the model. The case study illustrates that with the optimal charging strategies, less heat flux injection can help the borehole to reach a higher temperature so that the heating system is more efficient compared with boilers. This paper can benefit communities with seasonable borehole storage to provide clean but low-cost heating and also maximize PV penetration.</p