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Issue Info: 
  • Year: 

    2014
  • Volume: 

    10
Measures: 
  • Views: 

    141
  • Downloads: 

    48
Abstract: 

DUE TO THE DEPLETION OF FOSSIL FUEL RESOURCES AND SERIOUS GLOBAL WARMING EFFECTS IN THE LAST FEW YEARS, IT IS VITAL TO REPLACE PRESENT ENERGY CONVERSION TECHNOLOGY AND RESOURCES WITH A MORE SUSTAINABLE/RENEWABLE ENERGY SYSTEM [1]. SOLID OXIDE FUEL CELLS (SOFCS) WHICH ARE ONE OF THE CLEANEST AND MOST EFFICIENT ENERGY CONVERSION TECHNOLOGIES, HAVE ATTRACTED A GREAT DEAL OF ATTENTION RECENTLY AS A SUBSTITUTION FOR TRADITIONAL FOSSIL FUEL CONVERSION SYSTEMS. A CHALLENGING ISSUE IN THE DEVELOPMENT OF SOFCS IS TO IMPROVE Cathode PERFORMANCE BY MINIMIZING Cathode POLARIZATION RESISTANCE TO THE OXYGEN REDUCTION REACTION [2-4]. IN THIS STUDY, SMALL LOADING OF CERIA-BASED CATALYTIC NANOPARTICLESALONG WITH CATALYTICPALLADIUM NANOPARTICLES WERE CO-INFILTRATED INTO THE POROUS STRUCTURE OF LA0.8SR0.2MNO3 (LSM) Cathode BACKBONE AND THE ELECTROCHEMICAL PERFORMANCE OF THE CELLS WAS EVALUATED AT INTERMEDIATE TEMPERATURE RANGE OF 600-800OC. Cathode PERFORMANCE WAS INVESTIGATED BY ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY (EIS) AND DC POLARIZATION TECHNIQUE (CHRONOPOTENTIOMETERY) AT DC BIAS OF 200 MA/CM2 ON Cathode HALF CELLS. THE RESULTS INDICATED THAT ELECTROCHEMICAL PERFORMANCE OF CO-INFILTRATED Cathode IS SIGNIFICANTLY IMPROVED COMPARED WITH THAT OF LSM CathodeS SEPARATELY INFILTRATED WITH PD AND CERIA-BASED NANOPARTICLES. SCANNING ELECTRON MICROSCOPY (SEM) STUDIES SHOW RANDOM DISTRIBUTION OF DISCRETE NANO CATALYSTS IS FORMED IN THE VICINITY OF Cathode INTERFACE WHICH PROVES EFFECTIVENESS OF THE INFILTRATION TECHNIQUE FOR PERFORMANCE ENHANCEMENT OF Cathode ELECTRODES. LONG TERM STABILITY TESTS ARE IN PROGRESS TO EVALUATE AGGLOMERATION BEHAVIOR OF THE PD CATALYST IN THE PRESENCE OF CERIA NANOPARTICLES.

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Issue Info: 
  • Year: 

    2023
  • Volume: 

    10
  • Issue: 

    4
  • Pages: 

    281-290
Measures: 
  • Citations: 

    0
  • Views: 

    24
  • Downloads: 

    0
Abstract: 

Solid oxide fuel cells are a technology that can convert chemical energy directly into electrical energy. In the present study, single-phase lanthanium strontium manganate (LSM) nanoparticles with the nominal chemical formula La0. 8Sr0. 2MnO3 were successfully synthesized by the improved Pechini method. The infiltration of heterogeneous copper and cerium electrocatalysts on the Cathode was investigated. X-ray diffraction (XRD) was used to determine the phase composition. The microstructure and surface morphology of the synthesized powder was characterized using a scanning electron microscope (SEM). The coated composition was examined using energy dispersive spectroscopy (EDS) and elemental mapping images. The microstructure of the electrocatalysts seeded on the Cathode was studied by FESEM. The infiltration of 0. 5 M copper + 0. 5 M cerium nanoparticles (dimensions from 23 to 52 nm) with a broad distribution on the LSM Cathode surface was obtained. Results showed that using single-component solutions of copper and cerium nanoparticles with dimensions of 39-61 nm and 20-42 nm, respectively, were generated on the Cathode surface. The formation of agglomerated particles was observed as the cerium solution concentration increased. Secondary copper growth was observed as the copper solution concentration increased.

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Writer: 

BABAEI A.

Conference: 

IRANIAN FUEL CELL SEMINAR

Issue Info: 
  • Year: 

    2012
  • Volume: 

    5
Measures: 
  • Views: 

    139
  • Downloads: 

    114
Abstract: 

PERFORMANCE STABILITY OF LA0.8SR0.2MNO3 (LSM) Cathode PROMOTED WITH PALLADIUM CATALYST NANO-PARTICLES WAS INVESTIGATED AT CATALYST LOADINGS OF 0.08 MG CM-2 AND 0.25 MG CM-2 AND OPERATING TEMPERATURES OF 750 AND 850OC. ADDITION OF 0.08 MG CM-2 PDO TO THE MICROSTRUCTURE OF LSM ELECTRODE CONSIDERABLY DECREASED THE Cathode OVERPOTENTIAL FROM ABOUT 130 TO 21 MV AND THE PERFORMANCE OF THE CELL WAS QUITE REASONABLE DURING 44 H POLARIZATION OF THE CELL. THE HIGHER CATALYST LOADING OF 0.25 MG CM-2 WAS DETRIMENTAL TO THE PERFORMANCE STABILITY, ESPECIALLY AT HIGHER OPERATING TEMPERATURE OF 850OC. THE INSTABILITY OF THE CELL WAS MAINLY DUE TO THE AGGLOMERATION AND GRAIN GROWTH OF THE PDO CATALYST NANO PARTICLES AT THE SOLID OXIDE FUEL CELL (SOFC) OPERATION TEMPERATURE.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Conference: 

IRANIAN FUEL CELL SEMINAR

Issue Info: 
  • Year: 

    2012
  • Volume: 

    5
Measures: 
  • Views: 

    153
  • Downloads: 

    129
Abstract: 

POROUS LA0.8SR0.2MNO3 Cathode MATERIALS WERE PREPARED BY MECHANOCHEMICAL ROUT IN VARIOUS GRINDING TIMES. CARBON BLACK WAS EMPLOYED TO PRODUCE PORES. THE FORMATION OF LSM SINGLE PHASE WAS STUDIED BY X-RAY DIFFRACTION PATTERNS. POROSITY AND DENSITY AMOUNT WAS MEASURED BY MEANS OF ARCHIMEDES METHOD, ALSO CONTRACTION OF SINTERED SAMPLES WAS COMPARABLY MEASURED. FOR MORPHOLOGICAL STUDY THE SCANNING ELECTRON MICROSCOPY (SEM) IMAGES WERE USED. IT IS SHOWN THAT THE OPEN POROSITY GENERALLY DECREASES WITH INCREASING TEMPERATURE, BUT MILLING TIME GROWTH INCREASED THIS FACTOR. RELYING ON OPEN POROSITY AMOUNT AND DISTRIBUTION, RELATIVE DENSITY AND MICROSTRUCTURAL SCRUTINY THE PROPER SINTERING TEMPERATURE WAS DETERMINED. THE MICROSTRUCTURE INDICATES THAT THE GRAIN GROWS AS THE SINTERING TEMPERATURE INCREASES, WHICH LEADS TO THE DECREASE OF THE NUMBER OF OPEN PORES.

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Issue Info: 
  • Year: 

    2015
  • Volume: 

    3
  • Issue: 

    1
  • Pages: 

    25-32
Measures: 
  • Citations: 

    0
  • Views: 

    234
  • Downloads: 

    70
Abstract: 

In the present study, the effect of porosity on the Cathode microstructure (50: 50 wt. % LSM: YSZ) of a Solid Oxide Fuel Cell (SOFC) has been examined. A 3-D finite element method for Mixed Ionic and Electronic Conducting Cathodes (MIEC) is presented to study the effects of porosity on cell performance. Each microstructure was realized using the Monte Carlo approach with the isotropic type of growth rate. The effect of porosity on the Cathode of a solid oxide fuel cell involving the Three Phase Boundary Length (TPBL), electric conductivity of LSM phase, ionic conductivity of YSZ, mechanical behavior and tortuosity of the pore phase were explored in the present work. The Cathode having a porosity value between 31 and 34% revealed the maximum TPBL value as well as a high variation in the electrical conductivity of the LSM phase. Pore phase tortuosity was also decreased by increasing the porosity factor.

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Issue Info: 
  • Year: 

    2008
  • Volume: 

    5
  • Issue: 

    16
  • Pages: 

    49-58
Measures: 
  • Citations: 

    0
  • Views: 

    546
  • Downloads: 

    185
Abstract: 

Linear electric motors can drive a linear motion load without intermediate gears, screws or crank shafts. A linear synchronous motor (LSM) is a linear motor in which the mechanical motion is in synchronism with the magnetic field, i.e. the mechanical speed is the same as the speed of traveling magnetic field. In this paper, we obtained the electromagnetic thrust developed by a salient-pole LSM.

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Issue Info: 
  • Year: 

    1389
  • Volume: 

    4
Measures: 
  • Views: 

    293
  • Downloads: 

    0
Abstract: 

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Issue Info: 
  • Year: 

    1389
  • Volume: 

    4
Measures: 
  • Views: 

    362
  • Downloads: 

    0
Abstract: 

لطفا برای مشاهده چکیده به متن کامل (PDF) مراجعه فرمایید.

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Issue Info: 
  • Year: 

    2019
  • Volume: 

    8
  • Issue: 

    1
  • Pages: 

    16-33
Measures: 
  • Citations: 

    0
  • Views: 

    712
  • Downloads: 

    0
Abstract: 

Landslide susceptibility mapping (LSM) is a proper method to predicting landslide hazard risk in order to reducing its consequences. We prepared the LSM mapping of Kan basin by used of index of Entropy model and SVM-S. The validation of the produced maps is evaluated by used of the area under the curve ROC. Study area The study area is located on the north west of Tehran Province, between 35° 46′ and 35° 58′ N latitude and 51° 10′ to 51° 23′ E longitude. The area of the basin is 204. 385 km2 (Figure. 2 (a)). Material and methods In the present study we used of 8 parameters consisting the distance from river, distance from fault, distance from road, land use, rainfall, aspect, slope, elevation, and lithology. Distance from the road was computed from the road at the interval 200 m using ArcGIS software (Fig. 2f). The distance from road and distance from fault was calculated in same way (Figure. 2 d, h). The land use map has reclassified to 5 class (Figure. 2g). The lithology parameter has been obtained by the reclassification of the geological map of Tehran at the scale of 1: 100000 (Figure. 2h). The digital elevation model (DEM) was extracted from the 1: 50000 scale topographic maps. The parameters of slope degree (whit 5 classes), aspect layer were produced by used of the digital elevation model. (Figure. 2c & d). The topography layer was reclassified into 5 class (Fig. 2a). the introduced layers were used in this study according to the type of the models to produce of LSM maps. Entropy index Entropy is a measurement of the instability, imbalance, and uncertainty of a system (yang et al, 2010). The equations used to calculate the information coefficient dj representing the weight value for the parameter as a whole, are given as follows: pij=xij/(∑ _(i=1)^m▒ xij ) (1) (2) Ej=-k+∑ _(i=1)^m▒ pij ln⁡ (pij) K=〖 c(lnm)〗 ^(-1) (3) ((4 dj = EJ – 1 After calculating the total weight (wj) using Equation 5, the landslide risk of the case study is evaluated: (5) Hi = ∑ _(i=1)^m▒ xij In equation 5, H is the coefficient of landslide risk, wj is the final weigh of all the factors and Xij is the weight of each factor (zongji et al, 2010). The final landslide susceptibility map was prepared by the summation of weighted products of the secondarily parametric maps. H = (S×0/54) + (Df × 0/74) + (E × 0/082) + (Dr × 0/51) + (Dri × 0/51) + (A × 0/066) + (lu × 0/16) + (Lt × 0/0064) Support Vector Machine SVM algorithm as one of the most popular methods for solving regression problems has had significant results in landslide sensitivity zoning. consider a set of linear separable training vectors Xi (i = 1, 2, . . ., n). The training vectors consist of two classes, which are denoted as Yi = ± 1. The goal of SVM is to search an n-dimensional hyperplane differentiating the two classes by their maximum gap. Mathematically, it can be expressed as: 1⁄ 2=∥ w^2∥ (6) Y_i=((W. X_i )+)≥ 1 (7) A Lagrangian formulation is introduced to solve the problem (equation 8). Thus, the goal is now to minimize the Lagrangian L with to W and b and maximize with respect to λ i. For this reason, we used of following equation: L=1/2∥ w^2∥-∑ _(i=1)^n▒ Y^i ((W. X_i )+b)-1) (8) four types of SVM is existed: linear, polynomial, radial basis function (RBF) and sigmoid. The mathematical representation of each kernel (linear, polynomial, radial basis function, and sigmoid) is listed below, respectively: K (X_j 〖 . X〗 _i )= X_j^i. X_j K (X_j 〖 . X〗 _i )=(γ ∙ X_j^i+r). _ γ >0 K (X_j 〖 . X〗 _i )=e^(-γ 〖 (X_i-X_j)〗 ^2 ). _ γ >0 tanh (γ . X_i^T. X_j+r) γ , d, and r are user-controlled parameters, as their correct definition significantly increases the accuracy of the SVM solution. In the present research we used of Sigmoid function. To measure the validation of the models, we used of a relative ROC by comparing the existing landslide location with the two landslide susceptibility maps. The success rate curves were obtained by used of the 70% training dataset (29 landslide locations). ROC curve (AUC) represents the quality of the probabilistic model (it is ability to predict the occurrence or nonoccurrence of an event). Result and discussion The area of the low, moderate, and high classes based on the SVM model were found to be 109. 485 km2, 38. 7 km2, and 56. 2 km2, respectively, whereas based on landslide susceptibility map by used of index of entropy, the 118. 175 of the study area has low susceptibility risk, and the moderate, and high susceptibility zones have the 41. 2 km2, 45. 02 km2 of the study area, respectively (Fig. 3). Based on the entropy model, the 8 numbers of the landslides points located on the high-risk zone and the 8 numbers of the landslide points located on the moderate risk zone and low risk zone have 10 of the landslide points. Based on the LSM map produced by the SVM-S model, the 13 numbers of the landslide points located on the high risk zone and the 5 number of the landslide point located on the moderate-risk zone. The ROC plot assessment reveals that the AUC in the susceptibility map based on the index of entropy model was 0. 86 and the AUC in the susceptibility map based on the Logistic Regression model was 0. 91 (Fig. 5). Conclusion The high-risk zone on the LSM map produced by the SVM model is located in the north east and the west and south of the basin and based on the LSM map produced by the Entropy model is located in the north east and the south of the basin. The LSM map has produced in a regional scale, so further study need be carried out at the site-specific level to determine the exact extent site of the slope instability. Keywords: LSM, Index of Entropy model, Kan basin, Support Vector Machine, Sigmoid function, SVM-SIGMOID.

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Issue Info: 
  • Year: 

    2007
  • Volume: 

    4
  • Issue: 

    1
  • Pages: 

    89-106
Measures: 
  • Citations: 

    0
  • Views: 

    368
  • Downloads: 

    230
Abstract: 

The doped perovskite oxides such as La0.65 Sr0.30 MnO3-δ (LSM), La0.70 Sr0.30 CoO3-δ (LSC), La0.65 Sr0.30 FeO3-δ (LSF), La0.65 Sr0.30 NiO3-δ (LSN) and La0.60 Sr0.40 Co0.20 Fe0.80 O3-δ (LSCF) are proposed as alternate Cathode materials for solid oxide fuel cells working at reduced temperature (<1073 K). The critical requirement for their applicability is their chemical compatibility in conjunction with an alternate solid electrolyte, La0.9 Sr0.1 Ga0.8 Mg0.2 O3-δ (LSGM) without any new phase formation. To understand the chemical reactivity between these two components, thoroughly mixed different Cathode and LSGM electrolyte (1:1 by wt.) powders were pressed as circular components and subjected to annealing at 1573 K for 3 h in air. XRD and SEM were used for the characterization of the annealed samples. XRD measurements revealed that no new secondary phases were formed in LSM, LSC, and LSF with LSGM mixtures whereas LSN and LSCF with LSGM resulted in the formation of new secondary phases after high temperature treatment. The sintering shrinkage for all the components (Cathode + electrolyte mixture) was also estimated. For comparison of data, the individual powders (Cathode/electrolyte) were also compacted and studied in the same manner. The obtained results are discussed keeping in view the requirements that the candidate Cathode material must meet out with respect to its chemical compatibility to qualify for the LSGM based ITSOFC systems at 1073 K.

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