There have been increasing efforts to utilize energy by-products （EBP） all over the world. In the Czech Re- public fly ash is usually used in ceramic technology, es- pecially in brick manufacturing and for ceramic t...There have been increasing efforts to utilize energy by-products （EBP） all over the world. In the Czech Re- public fly ash is usually used in ceramic technology, es- pecially in brick manufacturing and for ceramic tiles. The average production of EBP is about Ig million tons per year. The range of potential products, where EBP could be used, is very wide and energy by-products have become an important raw material source. In this paper the attention was focused on class C fly ash and its usage in field of refractory materials. Experimental works were carried out on mixtures with fly ash and clay. There were also tested batches for lightweight fireclay bricks. The maximal amount of CFA should be up to 50%.展开更多
The article describes the experiences of alternative materials for the manufacturing of the refractory materi- als in the company P-D Refractories CZ a. s. The atten- tion is focused on energy by-products （EBP）. Ene...The article describes the experiences of alternative materials for the manufacturing of the refractory materi- als in the company P-D Refractories CZ a. s. The atten- tion is focused on energy by-products （EBP）. Energy by-products are generated during burning and desul- phurization in thermal power plants. Classical high-tem- perature -fly ash （class F.fly ash according to ASTM C618） is the most important and .fly ash from .fluidized technology （ class C-fly ash） is the second group. In the Czech Republic, power plants produce about 14 million tons of energy by-products every year. Utilization of these products in ceramic technology means a reduction of raw material costs and also it helps to reduce adverse environ- mental impact. Class F-fly ash （ FFA ） and cinder from high temperature combustion （CD） were used in light- weight insulation fireclay bricks. We can use these mate- rials as a grog and a lightening agent for materials with bulk density over 900 kg · m-3 and classification tem- perature up to 1 150 ℃. Class C.fly ash （CFA） is be- ing tested in a wide range of the refractory materials. For example, it can be used in lightweight fireclay bricks, fireclay bricks for stoves, acid-resistant fireclay bricks or refractory castables. The range of potential products, where EBP could be used, is very wide and energy by-products have become an important raw mate- rial source.展开更多
The paper is focused on computer simulation of natural vegetation propagation across two selected disturbed sites. Two sites located in the different environments, the abandoned sedimentation basin of a former pyrite ...The paper is focused on computer simulation of natural vegetation propagation across two selected disturbed sites. Two sites located in the different environments, the abandoned sedimentation basin of a former pyrite ore mine and the ash deposits of a power station, were selected to illustrate the proposed spatio-temporal model. Aerial images assisted in identifying and monitoring the progress in the propagation of vegetation. Analysis of the aerial images was based on varying vegetation coverage explored by classification algorithms. A new approach is proposed entailing coupling of a local dynamic model and a spatial model for vegetation propagation. The local dynamic model describes vegetation growth using a logistic growth approach based on delayed variables. Vegetation propagation is described by rules related to seed and its dispersal phenomena on a local scale and on the scale of outlying spreading. The disturbed sites are divided into a grid of microsites. Each microsite is represented by a 5 m x 5 m square. A state variable in each microsite indicates the relative vegetation density on a scale from 0 （no vegetation） to 1 （long-term maximum of vegetation density）. Growth, local vegetation propagation and the effects of outlying vegetation propagation in each cell are described by an ordinary differential equation with delayed state variables. The grid of cells forms a set of ordinary differential equations. The abandoned sedimentation basin and the ash deposits are represented by grids of 185 x 345 and 212 x 266 cells, respectively. A few case-oriented studies are provided to show various predictions of vegetation propagation across two selected disturbed sites. The first case study simulates vegetation growing without spatial propagations and delayed variables in the spatio-temporal model. The second and the third case studies extend the previous study by including local and outlying vegetation propagation, respectively. The fourth case study explores delayed impacts in the logistic growth term and the delayed outcome by vegetation propagation across the disturbed space. The performed case-oriented studies confirm the applicability of the proposed spatio-temporal model to predict vegetation propagation in short-term successions and to estimate approximate vegetation changes in long-term development. As a result, it can be concluded that remotely sensed data are a valuable source of information for estimates of model parameters and provide an effective method for monitoring the progress of vegetation propagation across the selected sites, spaces disturbed by human activities.展开更多
文摘There have been increasing efforts to utilize energy by-products （EBP） all over the world. In the Czech Re- public fly ash is usually used in ceramic technology, es- pecially in brick manufacturing and for ceramic tiles. The average production of EBP is about Ig million tons per year. The range of potential products, where EBP could be used, is very wide and energy by-products have become an important raw material source. In this paper the attention was focused on class C fly ash and its usage in field of refractory materials. Experimental works were carried out on mixtures with fly ash and clay. There were also tested batches for lightweight fireclay bricks. The maximal amount of CFA should be up to 50%.
文摘The article describes the experiences of alternative materials for the manufacturing of the refractory materi- als in the company P-D Refractories CZ a. s. The atten- tion is focused on energy by-products （EBP）. Energy by-products are generated during burning and desul- phurization in thermal power plants. Classical high-tem- perature -fly ash （class F.fly ash according to ASTM C618） is the most important and .fly ash from .fluidized technology （ class C-fly ash） is the second group. In the Czech Republic, power plants produce about 14 million tons of energy by-products every year. Utilization of these products in ceramic technology means a reduction of raw material costs and also it helps to reduce adverse environ- mental impact. Class F-fly ash （ FFA ） and cinder from high temperature combustion （CD） were used in light- weight insulation fireclay bricks. We can use these mate- rials as a grog and a lightening agent for materials with bulk density over 900 kg · m-3 and classification tem- perature up to 1 150 ℃. Class C.fly ash （CFA） is be- ing tested in a wide range of the refractory materials. For example, it can be used in lightweight fireclay bricks, fireclay bricks for stoves, acid-resistant fireclay bricks or refractory castables. The range of potential products, where EBP could be used, is very wide and energy by-products have become an important raw mate- rial source.
文摘The paper is focused on computer simulation of natural vegetation propagation across two selected disturbed sites. Two sites located in the different environments, the abandoned sedimentation basin of a former pyrite ore mine and the ash deposits of a power station, were selected to illustrate the proposed spatio-temporal model. Aerial images assisted in identifying and monitoring the progress in the propagation of vegetation. Analysis of the aerial images was based on varying vegetation coverage explored by classification algorithms. A new approach is proposed entailing coupling of a local dynamic model and a spatial model for vegetation propagation. The local dynamic model describes vegetation growth using a logistic growth approach based on delayed variables. Vegetation propagation is described by rules related to seed and its dispersal phenomena on a local scale and on the scale of outlying spreading. The disturbed sites are divided into a grid of microsites. Each microsite is represented by a 5 m x 5 m square. A state variable in each microsite indicates the relative vegetation density on a scale from 0 （no vegetation） to 1 （long-term maximum of vegetation density）. Growth, local vegetation propagation and the effects of outlying vegetation propagation in each cell are described by an ordinary differential equation with delayed state variables. The grid of cells forms a set of ordinary differential equations. The abandoned sedimentation basin and the ash deposits are represented by grids of 185 x 345 and 212 x 266 cells, respectively. A few case-oriented studies are provided to show various predictions of vegetation propagation across two selected disturbed sites. The first case study simulates vegetation growing without spatial propagations and delayed variables in the spatio-temporal model. The second and the third case studies extend the previous study by including local and outlying vegetation propagation, respectively. The fourth case study explores delayed impacts in the logistic growth term and the delayed outcome by vegetation propagation across the disturbed space. The performed case-oriented studies confirm the applicability of the proposed spatio-temporal model to predict vegetation propagation in short-term successions and to estimate approximate vegetation changes in long-term development. As a result, it can be concluded that remotely sensed data are a valuable source of information for estimates of model parameters and provide an effective method for monitoring the progress of vegetation propagation across the selected sites, spaces disturbed by human activities.
