Search results

Filters

  • Journals
  • Date

Search results

Number of results: 6
items per page: 25 50 75
Sort by:

Abstract

The reports of Intergovernmental Panel for Climate Change indicate that the growing emission of greenhouse gases, produced from the combustion of fossil fuels, mainly carbon dioxide, leads to negative climate changes. Therefore, the methods of mitigating the greenhouse gases emission to the atmosphere, especially of carbon dioxide, are being sought. Numerous studies are focused on so-called geological sequestration, i.e. injecting carbon dioxide to appropriate geological strata or ocean waters. One of the methods, which are not fully utilized, is the application of appropriate techniques in agriculture. The plant production in agriculture is based on the absorption of carbon dioxide in the photosynthesis process. Increasing the plant production directly leads to the absorption of carbon dioxide. Therefore, investigation of carbon dioxide absorption by particular crops is a key issue. In Poland, ca. 7.6 mln ha of cereals is cultivated, including: rye, wheat, triticale, oat and barley. These plants absorb approximately 23.8 mln t C annually, including 9.8 mln t C/yr in grains, 9.4 mln t C/yr in straw and 4.7 mln t C/yr in roots. The China, these cereals are cultivated on the area over 24 mln ha and absorb 98.9 mln t C/yr, including 55 mln tC/yr in grains, 36 in straw, and 7.9 mln t C/yr in roots. The second direction for mitigating the carbon dioxide emission into the atmosphere involves substituting fossil fuels with renewable energy sources to deliver primary energy. Cultivation of winter cereals as cover crops may lead to the enhancement of carbon dioxide removal from the atmosphere in the course of their growth. Moreover, the produced biomass can be used for energy generation.
Go to article

Abstract

The S-7 borehole log from the Sumina area (USCB Poland) revealed the presence of three basaltic veins originating from a basalt dyke. Coal interlayers in the rocks surrounding the basaltic veins have been coked to form natural coke. Photometric measurements revealed that the optical properties of the studied natural coke samples are characteristic of semi-graphite (Rmax > 9%). The natural coke matrix of all of the analyzed samples has a biaxial negative optical character. Vitrinite in the examined natural coke samples is characterized by a lower optical anisotropy than that of the natural matrix and it has a biaxial positive optical character. Vitrinite in almost all samples taken at locations more distant from the intrusion has a biaxial positive optical character. A reversal of the changes of the true maximum vitrinite reflectance and bireflectance with changing distance from the second basaltic vein has been observed. The temperature regime that acted upon the dispersed organic matter located in the immediate vicinity of the intrusion, estimated on the basis of the selected experimental data, is suggested to be higher than 750 °C.
Go to article

Abstract

The Low Temperature Joining Technique (LTJT) using silver compounds enables to significantly increase the thermal conductivity between joined elements, which is much higher than for soldered joints. However, it also makes difficult to measure the thermal conductivity of the joint. The Laser Flash Analysis (LFA) is a non-intrusive method of measuring the temperature rise of one surface of a specimen after excitation with a laser pulse of its other surface. The main limitation of the LFA method is its standard computer software, which assumes the dimensions of a bonded component to be similar to those of the substrate, because it uses the standard Parker’s formula dedicated for one-dimensional heat flow. In the paper a special design of measured specimen was proposed, consisting of two copper plates of different size joined with the sintered silver layer. It was shown that heat properties of these specimens can also be measured after modifying the LFA method. The authors adapted these specimens by masking the false heat signal sourced from the uncovered plate area. Another adaptation was introducing a correcting factor of the heat travel distance, which was calculated with heat-flow simulations and placed into the Parker’s formula. The heat-flow simulated data were compared with the real LFA measurement results, which enabled estimation of the joint properties, e.g. its porosity.
Go to article

This page uses 'cookies'. Learn more