Top PDF Particle-based Modeling of Ni-YSZ Anodes

Particle-based Modeling of Ni-YSZ Anodes

Particle-based Modeling of Ni-YSZ Anodes

These results also visualized in Figure 5.4. Figure 5.4 the electrolyte interface is to the left of the images and the gas phase boundary and current collector or electrode interface are at the right. In the top image the cermet particles are distinguished by type: blue for YSZ particles and gold for Ni particles. In the third picture the particles are colored by potential. Because the resistivity of the Ni phase is several orders of magnitude lower than that of the YSZ phase, the Ni phase particles have no visible differentiation in potential. The YSZ particles show considerable variation from the electrolyte potential (blue) to a potential differing from the electrode potential by the local half-cell open circuit potential. The second image clarifies this by removing the Ni particles. It is also easier to discern the groups of isolated YSZ particles as they show up as green in the image. These represent particles not connected to the larger ionic conduction paths to the electrolyte. This effect occurs because there can be no net Faradaic current without a both an electronically conducting pathway to transport the electrons to the current collector (electrode) and an ionically conducting pathway to transport the oxygen ions to the electrolyte surface. As can be seen in both the second image and the Faradaic current in the graph at bottom, the most intense volume of electrochemical activity is within 5 µm of the electrolyte interface. This extent of this volume can vary with the partial pressures of hydrogen and water, the relative abundance of Ni and YSZ particles, and the applied bias, but for the preliminary cases considered so far, the electrochemically active region remains within 15 µm of the electrolyte surface. This result has implications for anode design, as it directly implies that the design of the anode beyond this depth should be optimized to maximize fuel availability to the electrochemically active region, whether by reducing diffusion resistance for hydrogen fuel feeds or maximizing hydrogen production for hydrocarbon feeds.
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Fabrication and characterisation of a large area solid oxide fuel cell based on dual tape cast YSZ electrode skeleton supported YSZ electrolytes with vanadate and ferrite perovskite impregnated anodes and cathodes

Fabrication and characterisation of a large area solid oxide fuel cell based on dual tape cast YSZ electrode skeleton supported YSZ electrolytes with vanadate and ferrite perovskite impregnated anodes and cathodes

formation in hydrocarbon-based fuels and less sensitive to oxidation and reduction (redox) cycles than the state-of-the-art Ni (O) cermet does. However, two major problems are associated with the ceramic anode. First, compared with Ni (O) cermet, the electrode-performance characteristics of most of these materials are poor at intermediate temperatures (600-800 o C) because many of these oxides are not good catalysts for the oxidation of the fuel [8]. The introduction of reducible transition metals into the functional layer is one approach that can be used to enhance the catalytic activity [9]. The infiltration of ceramic conductors and catalytic metals (e.g. Ni, Pt and Pd) into porous scaffolds that had been pre-sintered onto the electrolyte is regarded as an effective method of promoting the electrode performance via producing nano-scale particles by in-situ sintering at relatively low temperatures [10,11, 12,13]. The nano-scale particles are able to increase the length of triple phase boundaries (TPBs) that provide the reaction sites for the fuel oxidation [14]. Second, the low conductivity of most ceramics in a fuel environment prohibits a configuration with a thick anode because of the large ohmic losses that it might cause [14]. In this study, we decided to use La 0.7 Sr 0.3 VO 3- (LSV red ) as the anode material as it has recently been shown to provide good electronic
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Catalytic Activity of Ni-YSZ composite as Anode for Methane Oxidation in Solid Oxide Fuel Cells

Catalytic Activity of Ni-YSZ composite as Anode for Methane Oxidation in Solid Oxide Fuel Cells

Natural gas has been exploited as an available energy source for solid oxide fuel cells in recent years. However, the problem of carbon deposition that forms on nickel-based anodes by using direct methane results in performance failure of cells. It is well known that the catalytic partial oxidation of methane is a good solution to suppress carbon formation. Herein, we present an investigation of the catalytic activity of Ni/YSZ cermet anodes as a function of the CH 4 /O 2 flow rate ratio (1 ≤ R in ≤ 5). The behavior of

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Characteristics of LaCo 1-x Ni x O 3-δ Coated on Ni/YSZ Anode using CH 4 Fuel in Solid Oxide Fuel Cells

Characteristics of LaCo 1-x Ni x O 3-δ Coated on Ni/YSZ Anode using CH 4 Fuel in Solid Oxide Fuel Cells

To overcome the shortcomings of the Ni/YSZ cer- met, many research groups have been developing alternative anodes for direct and practical utilization of hydrocarbon fuels [10-12]. However, alternative anodes of SOFCs must meet strict requirements such as good electrocatalytic activation, good electrical conductivity under reducing condition, chemical compatibility with electrolyte, and satisfied tolerance to carbon deposition and sulfur poisoning. Metal- based anodes including Cu, Co, W, etc., are not appropriate to utilize commercial hydrocarbon fuels, although they have exhibited excellent performance as alternative anodes. Noble metals including Ru, Pd, and Au are beyond consideration due to their high cost. Modification of the Ni/YSZ anode by mixed ionic and electronic conductive (MIEC) materials can be one approach to inhibit carbon deposition. A porous thin film of samarium-doped ceria (SDC) on the Ni/YSZ anode improves the cell performance and minimizes carbon deposition [13,14]. Due to MIEC
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Optimization of Flow Rate for Improving Performance and Stability of Ni-YSZ based Solid Oxide Fuel Cells Using CH4 Fuel

Optimization of Flow Rate for Improving Performance and Stability of Ni-YSZ based Solid Oxide Fuel Cells Using CH4 Fuel

particle size, and the addition of various catalysts to prevent carbon formation all affect the rate of carbon deposition. Moreover, carbon has diverse structures including adsorbed polymeric, vermicular filaments, carbide, and graphitic, which affect carbon reactivity and result in degradation in catalytic activation [7-8]. Several studies of the characteristics of carbon deposited on Ni-YSZ have been sought to overcome carbon deposition. Alzate-Restrepo et al. [9] found that when current density was increased, less carbon was deposited and that, with increased operating time and anode thickness, deposited carbon became more difficult to remove. Lin, Zhan et al. [10] found that Ni-YSZ anode- supported SOFCs can be operated stably with high applied current density. It is also well known that carbon deposition is suppressed at high S/C ratios, lower operating temperatures, and when new anode catalysts such as ceria, ceramic anode and Alkali metals are used [11-19]. The utilization of carbon as a fuel for solid oxide fuel cells was further investigated by Ihara et al [20]. The CO 2 generated by the
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Synthesis and Electrochemical Characterization of Novel Category Si3-xMxN4 (M= Co, Ni, Fe) Anodes for Rechargeable Lithium Batteries

Synthesis and Electrochemical Characterization of Novel Category Si3-xMxN4 (M= Co, Ni, Fe) Anodes for Rechargeable Lithium Batteries

terms of specific capacity values at regular intervals and columbic efficiency is displayed in Table 1. From the table, it is evident that the coulumbic efficiency of all the select category silicon nitride based anodes are excellent, despite the unavoidable initial irreversible capacity loss problem. Further, it is understood that the Si 3-x Fe x N 4 anode exhibits the highest capacity and the rest of the Si 3 N 4 and Si 3- x M x N 4 [M = Co, Ni] anodes possess better capacity retention capability, as obvious from Fig.5 also.

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Modeling Prefix and Particle Verbs in GermaNet

Modeling Prefix and Particle Verbs in GermaNet

Another type of word-initial elements, which can be systematically modeled in class 3, repre- sents preverbs indicating lexical aspect or Ak- tionsart ‘manner of action’. On the one hand, this includes ingressive markers such as the prefix er- (e.g., erklingen ‘start to sound’) and the particle los (e.g., loslaufen ‘start running’). On the other hand, the prefix ver- (e.g., verglühen ‘burn out’) as well as some word formations with the parti- cles auf and aus characterize egressive verbs
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Modeling and Design For Objective Charged
Particle Lens

Modeling and Design For Objective Charged Particle Lens

The electron lenses suffer from many different types of imperfections through the image formation process. These defects are different according to the function of the charged particle lens. However, the objective electron lenses suffer from two main important defects namely; spherical and chromatic aberrations. The spherical aberration is caused by the in- homogeneity of the lens field affecting the off-axis rays, which reduces the focal length for electron rays passing the outer zones of the lens. As a result, electrons from a point object crossing the optical axis at different angles is imaged as a disc with a minimum diameter of s C s 3
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Numerical modeling of relativistic particle shock acceleration

Numerical modeling of relativistic particle shock acceleration

Thus, for a strong non-relativistic shock, i.e. r = 4, one obtains the differential particle spectrum as, f (p) ∝ p −4 ∝ E −2 . The remarkable point in the first order Fermi mecha- nism theory is that the calculated spectral index value of −2, is very close to the overall spectral index value of the differ- ential cosmic ray spectrum observed on Earth. Of course it is understood that the feature of non-relativistic shock acceler- ation theory lies in the fact that the distribution of accelerated particles is scale-independent, i.e. a power-law with a spec- tral index that depends only on the velocity compression ratio r. Nevertheless, as we will discuss later-on, this result does not carry over to relativistic shocks because of their strong plasma anisotropy. As a consequence, while power-laws are indeed created, the index becomes a function of the flow speed, the field obliquity, and the nature of the scattering, all of which closely control the degree of particle anisotropy. Moreover, except of the standard value of r = 4 for strong non-relativistic shocks, the choice of the canonical compres- sion ratio r = 3 is a well-known result for a relativistic purely hydrodynamic shock. However, one can envisage situations where the magnetic field becomes dynamically important. The classic example is the termination shock of the Crab pulsar wind where Kennel and Coroniti (1984) observed that strong fields can weaken magnetohydrodynamic shocks con- siderably. Double et al. (2004) determined deviations from r = 3 in highly relativistic shocks in the common cases where pressure anisotropy is significant. These deviations can ei- ther strengthen or weaken the shock, depending on the nature of the pressure anisotropy, which must be a significant func- tion of the shock obliquity thus, in a relativistic shock one would anticipate the spectral index to be a function of ψ.
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Flexible Structure Impact Modeling With a Particle Method.

Flexible Structure Impact Modeling With a Particle Method.

There has been an extensive amount of research done involving particle models, finite element analysis and collision detection/resolution for the textile and computer graphics industries. Free-falling cloth, the draping of cloth over solid objects (i.e. tables, chairs, blocks, balls, etc.) and modeling clothing on the human body are some of the most common examples. Other examples include flags waving and drapes blowing in the wind. One interesting case done by Huh et al. (2001) involves cloth draped over a solid ring; a ball is dropped on the cloth so both the ball and the cloth fall through the ring. Also, research done by O’Brien et al. (1997) introduces the combination of active and passive simulations for secondary motion. Some interesting examples examined through their simulations are: a gymnast on a trampoline, a bungee jumper, a gymnast vaulting on a mat, a girl swinging while wearing a skirt, and kites in the air. The primary contribution of the work is to examine three types of coupling: full, partial and one-way which they describe through the example of a basketball going through the net.
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Thermodynamic Modeling of the Undercooled Liquid in the Ni  Zr System

Thermodynamic Modeling of the Undercooled Liquid in the Ni Zr System

Using thermodynamic data obtained over a wide range of temperatures, a thermodynamic assessment of the Ni–Zr system was carried out. The associated solution model was applied to describe the short range ordering in the liquid, and the glass transition was treated as a second order transition, using the Hillert–Jarl functions. The driving force of crystallization, and the time–temperature–transformation (TTT) curves were estimated from the optimized parameter set, and compared with experimental data and the results of previous thermodynamic assessments. Taking into account the low temperature thermodynamic data, the calculated driving force was found to have decreased compared to the previous assessments. Consequently, the nose of the TTT curve was shifted to higher times.
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Empirical modeling of the fine particle fraction for carrier-based pulmonary delivery formulations

Empirical modeling of the fine particle fraction for carrier-based pulmonary delivery formulations

pairs. A total of 51 different input vectors were used at the first stage of modeling by Cubist, randomForest, and monmlp packages for R environment. The best results were obtained for 28 input vectors for artificial neural network-based models with RMSE and NRMSE equal to 5.76 and 13%, respectively. A comparison of the best models created for all modeling methods is shown in Table 4. Thus, a further modeling process with a genetic program- ming method and fuzzy systems was performed using 28 input vectors. The structure of the data set is presented in Table 3. Models created using rule-based systems like Cubist and randomForest showed an NRMSE error that was slightly higher than artificial neural networks (by 3% and 2%, respectively). The best fuzzy logic model had an RMSE and an NRMSE of 5.5 and 12%, respectively. The mathematical model was characterized by an RMSE of 4.9. Moreover, the genetic algorithm performed further auto- matic input vector reduction, ending up with only eleven input variables selected from the database (Equation 3). The observed versus predicted plot for the model is pre- sented in Figure 3.
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A Comparative Study of YSZ Suspensions and Coatings

A Comparative Study of YSZ Suspensions and Coatings

To conclude, the commercial suspensions prepared in industrial scale and with optimized procedures seem to show more stability and provide reproducibility in the coatings. In addition, manipulation of microstructures is always possible. An interesting distinction in the behaviors of suspensions with variation in particle shape (and a small size change) is observed when the axial injection in axial III torch was used. The reasons for varying role of the suspension viscosity and surface tension in the case of radial and axial injection, as observed here, as well as the potential role of the particle shape (and less probably small particle size change) on significant change of the microstructure remain the matter of detailed droplet and in-flight collected particles investigation. Therefore, the exact reason for this difference remains the matter of further investigation.
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modeling genetic algorithms with interacting particle systems

modeling genetic algorithms with interacting particle systems

Section 2.1 recalls and comments on the schema theory, modeling the evolution of schemata. Section 2.2 presents and comments on an approach borrowed from physics, approximating the evolution of population fitness distributions by some of their moments. Section 2.3 focuses on the evolution of allelic marginal distributions. This latter point of view has been given much attention in the last 5 years, and led to a number of alternative algorithms, that are not guaranteed to find the global optimum, but which might converge quicker than GAs.

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Role of Dopants on Ceria based Anodes for IT SOFCs Powered by Hydrocarbon Fuels

Role of Dopants on Ceria based Anodes for IT SOFCs Powered by Hydrocarbon Fuels

The behavior of these ceria-based anodes under described conditions and its capability to operate in the presence of hydrogen sulfide (up to 500 ppm) offers great benefits in terms of energy and environmental management by eliminating the requirements for costly desulfurization units. It has been demonstrated that the selection of the appropriated dopant allows improving different properties of anode material in order to increase its fuel flexibility and poison tolerance. Nevertheless, complementary strategies could be additionally adopted in order to improve the cell performance and increase the reasonable power densities obtained. For example, the reduction of electrolyte thickness to values close to or even lower than 100 µ m is a crucial point for minimizing the internal cell resistances. Additionally, another interesting approach could be related to the anode microstructure, by increasing the active anode area that expands the interfacial contact area between the catalyst, the current collector and the fuel (TPB) and theoretically improves the cell performance. In both sense, at present, we are optimizing the tape-casting method for the preparation of thinner SOFC electrolytes as well as the controlled preparation method of nanostructured anodes that
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Fuzzy modeling with the particle swarm optimization algorithm

Fuzzy modeling with the particle swarm optimization algorithm

Na wstępie warto zaznaczyć, że zarówno algorytm optymalizacji rojem cząstek, jak i algorytm k-średnich pozwalają spojrzeć na problem klasteryzacji bardziej z perspektywy rozl[r]

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Hydrogen oxidation on Ni-based electrocatalysts: the

Hydrogen oxidation on Ni-based electrocatalysts: the

reaction, exchange current density, alkaline medium, DFT, hydrogen binding energy, hydroxide.. 30.[r]

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Whole-Lung Airflow and Particle Transport/Deposition Modeling.

Whole-Lung Airflow and Particle Transport/Deposition Modeling.

submillimeter alveolar structures. As an alternative, several investigators have used numerical methodology to shed light on alveolar mechanics and particle transport and deposition in these alveoli. Most of the initial numerical analysis was based on simplified 2- D alveolar structures. Tsuda et al., [197] conducted numerical analysis of alveolar flow and reported chaotic mixing of flow in the alveolar region. The model developed by Tsuda et al., [197] consists of an axisymmetric 2D straight tube with a torus attached on the outer surface representing an alveolus. The model wall was displaced using rhythmic expansion and contraction to represent alveolar wall movement. Tsuda et al., [198] used flow visualization technique to demonstrate alveolar flow recirculation in a rhythmically ventilated rat lung. They verified their previous numerical results demonstrating chaotic irreversible alveolar flow characterized by stagnation saddle points associated with alveolar vortices. Haber and Tsuda [199] numerically analyzed the particle deposition pattern in a rhythmically expanding alveolus. The alveolus and alveolar duct were modeled as a spherical cap attached at its rim to a circular opening in an expanding plane. The results showed that the particle deposition pattern considerably varies with the alveolar wall motion. Later Haber et al., [200] analyzed the effects of gravity and alveolar wall movement on deposition of particles with size ranging from 0.5 𝜇m to 2.5 𝜇m. They found that the submicron particles are significantly influenced by the alveolar flow patterns compared to the micron sized particles. Henry et al., [201] obtained similar results using numerical analysis alveolar flow pattern and particle deposition in a 9-cell alveolated duct model.
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modeling of controlled particle deposition on to electronically conducting surfaces

modeling of controlled particle deposition on to electronically conducting surfaces

([SHULPHQWDO UHVXOWV SUHYLRXVO\ UHSRUWHG E\ %DKPDQL >@ KDYH EHHQ VLPXODWHG XVLQJ WKH WUDMHFWRU\ DQDO\VLV )RU WKLV V\VWHP JUDYLW\ IRUFH GRHV QRW KDYH DQ LPSRUWDQW LPSDFW RQ WKHUDWHRIGH[r]

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Scientific Modeling and FPGA Implementation of Particle Swarm  Optimization

Scientific Modeling and FPGA Implementation of Particle Swarm Optimization

(Abridged as PSO) is a novel populace based stochastic pursuit calculation and an option answer for the complex non- straight streamlining issue. The PSO calculation was first presented by Dr. Kennedy and Dr. Eberhart in 1995 and its essential thought was initially enlivened by reenactment of the social conduct of creatures, for example, winged animal running, angle tutoring et cetera. It depends on the common procedure of gathering correspondence to share singular learning when a gathering of flying creatures or creepy crawlies seek nourishment or relocate et cetera in a looking space, albeit all feathered creatures or bugs don't know where the best position is. Be that as it may, from the idea of the social conduct, if any part can discover an attractive way to go, whatever is left of the individuals will take after rapidly. A few scientists have created diverse answers for direct and non-liner streamlining issues. Scientifically an enhancement issue has a wellness work, portraying the issue under an arrangement of imperatives which speaks to the arrangement space for the issue.
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