Metal(oxide)-zeolite bifunctional catalysts have been the subject of considerable attention from researchers in both academic and industry,due to their superior activity and stability in various heterogeneous catalyti...Metal(oxide)-zeolite bifunctional catalysts have been the subject of considerable attention from researchers in both academic and industry,due to their superior activity and stability in various heterogeneous catalytic processes[1–3].Based on the different metal loading sites,these bifunctional catalysts can be categorized as follows:(a)metal species loaded on the outer surface of zeolite crystals,(b)metal species encapsulated within the channels or cavities of zeolites,and(c)metal species incorporated into the zeolite framework(Fig.1).Metal species in type(b)and(c)samples are stabilized by the zeolite frameworks,resulting in excellent thermal and hydrothermal stability during catalytic reactions,especially under harsh conditions,as well as unique shape-selectivity.However,the complex synthesis procedures make large-scale preparation of these catalysts impractical.In contrast,a type(a)sample can be achieved via the simple impregnation;nevertheless,migration of metal species and their aggregation into larger particles often occur during the calcination and reduction processes.展开更多
This study evaluates the effects of the initial situation of the site (slope and quality of the soil with its resistance characteristics), building loads, support and drainage/non-drainage on the safety and stability ...This study evaluates the effects of the initial situation of the site (slope and quality of the soil with its resistance characteristics), building loads, support and drainage/non-drainage on the safety and stability of sloping sites. The objective is to contribute to the stabilization of sloping sites under building loads. Considering a sloping site under building loads in the city of Bujumbura in Burundi facing the problem of instability, an experimental study of the site’s soils is first carried out in the laboratory. Secondly, an analysis by numerical simulation of stability is carried out based on 3 main simulation cases: By first considering an initial situation (unloaded), then a loaded situation without support and a loaded situation with support. The calculation is carried out in a drained state and in an undrained state, with a water table blocked at depth to simulate the reality on the ground. Three buildings of different levels are designed according to the existing buildings and their loads are determined for the loaded case simulations. The results of the analysis thus make it possible to assess the effect on safety and stability of: 1) the slope of the unloaded site and the quality of the soil with its resistance characteristics, 2) the loads of the buildings or their intensive increase, 3) the drained or undrained state of the soil on the site, 4) the support or non-support of the unloaded or loaded, drained or undrained sloping site.展开更多
It is well recognized that the voltage stability of a power system is affected by the load model and hence, to effectively analyze the reactive power compensation of an isolated hybrid wind-diesel based power system, ...It is well recognized that the voltage stability of a power system is affected by the load model and hence, to effectively analyze the reactive power compensation of an isolated hybrid wind-diesel based power system, the loads need to be considered along with the generators in a transient analysis. This paper gives a detailed mathematical modeling to compute the reactive power response with small voltage perturbation for composite load. The composite load is a combination of the static and dynamic load model. To develop this composite load model, the exponential load is used as a static load model and induction motors （IMs） are used as a dynamic load model. To analyze the dynamics of IM load, the fifth, third and first order model of IM are formulated and compared using differential equations solver in Matlab coding. Since the decentralized areas have many small consumers which may consist large numbers of IMs of small rating, it is not realistic to model either a single large rating unit or all small rating IMs together that are placed in the system. In place of using a single large rating IM, a group of motors are considered and then the aggregate model of IM is developed using the law of energy conservation. This aggregate model is used as a dynamic load model. For different simulation studies, especially in the area of voltage stability with reactive power compensation of an isolated hybrid power system, the transfer function AQ/AV of the composite load is required. The transfer function of the composite load is derived in this paper by successive derivation for the exponential model of static load and for the fifth and third order IM dynamic load model using state space model.展开更多
基金financially supported by the National Key R&D Program of China(2024YFE0101100)the National Natural Science Foundation of China(22475112,22305132,22305155)+1 种基金the China Postdoctoral Science Foundation(2023M732323)the Postdoctoral Fellowship Program of CPSF(GZC20231679).
文摘Metal(oxide)-zeolite bifunctional catalysts have been the subject of considerable attention from researchers in both academic and industry,due to their superior activity and stability in various heterogeneous catalytic processes[1–3].Based on the different metal loading sites,these bifunctional catalysts can be categorized as follows:(a)metal species loaded on the outer surface of zeolite crystals,(b)metal species encapsulated within the channels or cavities of zeolites,and(c)metal species incorporated into the zeolite framework(Fig.1).Metal species in type(b)and(c)samples are stabilized by the zeolite frameworks,resulting in excellent thermal and hydrothermal stability during catalytic reactions,especially under harsh conditions,as well as unique shape-selectivity.However,the complex synthesis procedures make large-scale preparation of these catalysts impractical.In contrast,a type(a)sample can be achieved via the simple impregnation;nevertheless,migration of metal species and their aggregation into larger particles often occur during the calcination and reduction processes.
文摘This study evaluates the effects of the initial situation of the site (slope and quality of the soil with its resistance characteristics), building loads, support and drainage/non-drainage on the safety and stability of sloping sites. The objective is to contribute to the stabilization of sloping sites under building loads. Considering a sloping site under building loads in the city of Bujumbura in Burundi facing the problem of instability, an experimental study of the site’s soils is first carried out in the laboratory. Secondly, an analysis by numerical simulation of stability is carried out based on 3 main simulation cases: By first considering an initial situation (unloaded), then a loaded situation without support and a loaded situation with support. The calculation is carried out in a drained state and in an undrained state, with a water table blocked at depth to simulate the reality on the ground. Three buildings of different levels are designed according to the existing buildings and their loads are determined for the loaded case simulations. The results of the analysis thus make it possible to assess the effect on safety and stability of: 1) the slope of the unloaded site and the quality of the soil with its resistance characteristics, 2) the loads of the buildings or their intensive increase, 3) the drained or undrained state of the soil on the site, 4) the support or non-support of the unloaded or loaded, drained or undrained sloping site.
文摘It is well recognized that the voltage stability of a power system is affected by the load model and hence, to effectively analyze the reactive power compensation of an isolated hybrid wind-diesel based power system, the loads need to be considered along with the generators in a transient analysis. This paper gives a detailed mathematical modeling to compute the reactive power response with small voltage perturbation for composite load. The composite load is a combination of the static and dynamic load model. To develop this composite load model, the exponential load is used as a static load model and induction motors （IMs） are used as a dynamic load model. To analyze the dynamics of IM load, the fifth, third and first order model of IM are formulated and compared using differential equations solver in Matlab coding. Since the decentralized areas have many small consumers which may consist large numbers of IMs of small rating, it is not realistic to model either a single large rating unit or all small rating IMs together that are placed in the system. In place of using a single large rating IM, a group of motors are considered and then the aggregate model of IM is developed using the law of energy conservation. This aggregate model is used as a dynamic load model. For different simulation studies, especially in the area of voltage stability with reactive power compensation of an isolated hybrid power system, the transfer function AQ/AV of the composite load is required. The transfer function of the composite load is derived in this paper by successive derivation for the exponential model of static load and for the fifth and third order IM dynamic load model using state space model.
