Mathematical Model of the Shell with the Infill for Retaining Structures

A description of finite element model and analysis of a shell with an infill is performed. A large diameter thin cylindrical shell structure with the edge leaning against compressible foundation soil is analyzed. Different materials are considered individually for the models of each structure shell and infill component (metal or reinforced concrete shell, and granular or elastic infill in a shell and foundation soil loaded by the structure). Contact conditions between 1) the infill and the shell’s inner surface and 2) between the foundation material and the shell edge are analyzed. An example of calculating strain conditions in the shell according to the proposed finite element model and tasks of its development process and specification are provided in this paper

Stability of Thin Shell with Infill Gravity Structures against Lateral Loads

The article refers to construction of shell filled with soil facilities. The main advantages of this type of structures is the minimized use of new materials and the utilized composite action of materials forming the structure. The construction heavily utilizes the soils directly at the building site. These structures have to resist external horizontal loads under the action of its own weight without overturning for their stability and sustainability. The lateral loads can be caused by soils, berthing impact, and mooring forces, and the structure\u27s capacity can be modeled under these horizontal loads. The purpose of this study is to develop a theoretical model to predict the structure\u27s response to the applied horizontal loads and to verify the model by finite elemental modelling and analysis. The finite element modelling and analyses were performed by using ANSYS / LS-Dyna software to verify the theoretical model. The theoretical model is developed through the use of failure planes based on the limit equilibrium conditions. The minimum horizontal load that causes overturning of the shell is calculated using the theoretical model and then is confirmed by numerical simulations. The results of the numerical simulation are correlated with the results of the theoretical model. Discrepancies between the theoretical and numerical modelling results are presented, and possible causes of the discrepancies are discussed. The study helps to provide a good understanding of the mechanisms involved in the overturning stability of these structures. It is also useful for the theoretical model development and can be utilized in the design of these structures

CeO2-supported Pt–Ag bimetallic catalysts for 4-nitrophenol reduction

The present work is focused on designing of ceria-supported Pt–Ag bimetallic catalysts for 4-nitrophenol reduction with NaBH4. The series of ceria-supported monometallic (Pt or Ag) and bimetallic Pt-Ag catalysts are prepared by wetness impregnation followed by calcination in air at 500 ◦С. The bimetallic 2-xPtxAg/CeO2 samples with a total metal loading of 2.0 wt% and Pt:Ag mass ratios of 1.5:0.5, 1:1, and 0.5:1.5 show superior activity caused by the formation of bimetallic Pt–Ag species upon simultaneous reduction of highly dispersed interplaying PtOx and silver species. The Ag addition to Pt and the conditions of the bimetallic catalyst treatment ensure the fine-tuning of the metal–support interactions and enhance the catalyst activity. The optimal Pt:Ag ratio in the bimetallic Pt-Ag catalysts depends on the sample pretreatment affecting the composition and dispersion of the surface Pt–Ag species formed. For samples calcined in air at 500 ◦С for 2 h and reduced with NaBH4 in the reaction mixture, the highest activity is achieved for the 1Pt1Ag/CeO2 catalyst characterized by the complete 4-NP conversion at 23 ◦С in 3 min with an apparent rate constant kapp of 2.3 × 10− 2 s − 1 and a specific rate constant kMe of 223,500 s − 1 mol− 1. For the air-calcined samples pre-reduced in H2/Ar at 300 ◦С for 30 min, the highest activity is achieved in case of 0.5Pt1.5Ag/CeO2 catalyst characterized by 94% 4-NP conversion at 23 ◦С in 3 min with the kapp of 1.6 × 10− 2 s − 1 and the kMe of 152,100 s− 1 mol−

Horizontal and vertical distribution of Omul in spring : effective hydroacoustic approaches

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