Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 16
items per page: 25 50 75
Sort by:

Abstract

Krill population structure was studied in Western Antarctic in austral spring and summer 1986/87. At the end of October and the beginning of November in the waters around Elephant Island the mean krill length was 44 mm and sexually mature specimens dominated. Juveniles were absent. In the Bransfield Strait the mean E. superba length was 43 mm. and males slightly overdominated females. The share of females with spermatophores and of immature females was higher than in the Elephant Island area. Juveniles were also not recorded. Krill was most diversified around Elephant Island in January; juveniles and females with ovaries filled with eggs were recorded. It was found that 84% of krill population was infested by ciliate protozoans (Apostomatida).
Go to article

Abstract

In the paper, on the basis of our studies and the available literature data, a model of changes in the number of active centers corresponding to the structure of the reactive coal particle has been developed. A new distribution function that links the specific surface area of a particle with its porosity and reaction degree has been proposed. An equation for estimation of changes in this parameter during the reaction, on the basis of the initial value, has been presented. In the range of our data and the analysis of the literature data, the model, with satisfactory accuracy, describes internal structural changes of coal and coal char particles. The present results may constitute a basis for complex modelling of coal conversion processes. Based on the results it was found that the total active centres are related to the internal surface area and porosity of the particle. For a specific coal type, this value depends on the porosity, true density and size of the particle. Changes in total active centres, when these structural properties during thermal conversion of coal are considered, are described in equations.
Go to article

Abstract

The rigid finite element method (RFEM) has been used mainly for modelling systems with beam-like links. This paper deals with modelling of a single set of electrodes consisting of an upper beam with electrodes, which are shells with complicated shapes, and an anvil beam. Discretisation of the whole system, both the beams and the electrodes, is carried out by means of the rigid finite element method. The results of calculations concerned with free vibrations of the plates are compared with those obtained from a commercial package of the finite element method (FEM), while forced vibrations of the set of electrodes are compared with those obtained by means of the hybrid finite element method (HFEM) and experimental measurements obtained on a special test stand.
Go to article

Abstract

As of the spring of 2017, the HAŁDY Database is available on the Polish Geological Institute – NRI website. The geodatabase contains information and data on waste mineral raw materials collected on old heaps, industrial waste stock-piles and in post-mining settlers, from the Polish part of the Sudety Mountains. The article presents the types of data and information contained in the geodatabase and the methodology for their collection. As a result of four-year research works, field reconnaissance, archives and geological basic research, 445 objects of former mining and mineral processing were inventoried. There are 403 mine heaps, 16 industrial settlers, 23 stock-piles and 3 external dumps. These are mainly objects after coal mining and metal ores, including post-uranium. The greatest opportunities for the economic use of waste are associated with coal sludge accumulated in settlers of the liquidated Lower Silesian Coal Basin. The material from stone heaps after polymetallic, iron and fluorite ore mining is also easy to use. The issue of the economic use of post-flotation copper ore waste or the recovery of metals (including gold) from dumps of arsenic mining remains open. The limitation here is the efficiency of metal recovery technologies and environmental restrictions. Some of the objects are located in protected areas, which excludes the possibility of waste management. Some stock-piles and heaps should be carefully reclaimed and covered by environmental monitoring, due to their harmful impact on environmental components.
Go to article

Abstract

At the current stage of diagnostics and therapy, it is necessary to perform a geometric evaluation of facial skull bone structures basing upon virtually reconstructed objects or replicated objects with reverse engineering. The objective hereof is an analysis of imaging precision for cranial bone structures basing upon spiral tomography and in relation to the reference model with the use of laser scanning. Evaluated was the precision of skull reconstruction in 3D printing, and it was compared with the real object, topography model and reference model. The performed investigations allowed identifying the CT imaging accuracy for cranial bone structures the development of and 3D models as well as replicating its shape in printed models. The execution of the project permits one to determine the uncertainty of components in the following procedures: CT imaging, development of numerical models and 3D printing of objects, which allows one to determine the complex uncertainty in medical applications.
Go to article

This page uses 'cookies'. Learn more