Results 1 - 10 of 1817
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[en] Geophysical methods used in the determination of geothermal potential by geophysical investigations in the Karbinci-Tarinci area included as follows: detailed reflective seismic scanning, geomagnetic profiling, geo electric probe and electromagnetic VLF prospecting. The site investigated consists of rocks of Precambrian, Mesozoic (Jurassic), Tertiary (Paleogene Neogene) and Quaternary age. From earlier investigations carried out in the wider vicinity and from investigations carried out by the present authors, one can expect occurrence geothermal water in the area. (Author)
[en] Determination of macro elements and trace elements in apple fruits was carried out by ICP-AES method. Apples were picked up fresh in December 2005. Seven different types of apples from different parts of the country were selected. Apples were sliced into large pieces, dried, and after grinding were dissolved in nitric acid (HNO3) and hydroperoxide (H2O2). After digestion, multi-element analysis was carried out. Data obtained were compared to published values for trace elements in apples in other regions of the world. Data obtained indicated that the concentration of trace elements in apples were within the values and data in other regions of the world. (Author)
[en] Many different processes of production of lightweight refractories are well known over the World. Traditional production of lightweight refractories is by addition of combustibles or by a special frothing process. This work is concerned with hydrothermal of lightweight refractories from rice husk ash. The rice husk ash, used in present investigations were from Kocani region, R. Macedonia. The chemical analysis of the rice husk ash shows that it contains 91,8 - 93,7% SiO2 and some alkaline and alkaline earth oxides. Microscopic and X - ray diffraction examinations of the rice husk ash have shown that it is composed of cristobalite, tridimite and amorphous silica. The composition of the mixture for lightweight refractory brick production is 93,4% rice husk ash and 6,6% Ca(OH)2. The mixtures were well mixed, moistened and pressed at 5 - 10 MPa. The hydrothermal reactions between calcium hydroxide and rice husk ash over the temperature range 80 - 160oC were investigated. The period of autoclave treatment was from 2 to 72 h. After the hydrothermal treatment of the samples, the mineralogical composition, bulk density, density, cold crushing strength, porosity, refractoriness and thermal expansion were examined. Analysing the properties of the obtained samples it can be concluded that from rice husk ash and calcium hydroxide under hydrothermal condition it is possible to obtain lightweight acid refractory material with high quality.(Author)
[en] The report aims at assessing the progress in adopting comprehensive environmental protection strategies at the local level. The whole project was carried out by the Regional Environmental Center for Central and Eastern Europe (REC) in collaboration with the Ministry for Urban Planning, Construction and Environmental of Republic of Macedonia (MUPCE). The REC and MUPCE identified four different municipalities to develop different modules of LEAPs with using the same methodology approach, which can be used as a pilot projects for other, more than hundred municipalities in Macedonia. These municipalities are: 1) Centar - one of the seven municipalities in the city Skopje, which occupies central part of the capital of Macedonia, as a typical urban area; 2) Veles as a typical industrial area, situated in the central part of the Republic of Macedonia, and considered as the most polluted region in the country; 3) Zrnovci - situated in the eastern part of Macedonia, a typical agricultural area, mainly for rice production; 4) Gevgelija as a transboundary and transit area
[en] The computer development aided reserch systems in the investigations of the characteristics of the surface layar forms conditions for decreasing of the measuring uncertainty. Especially important is the fact that the usage of open and self made measuring systems accomplishes the demands for a total control of the research process. This paper describes an original personal computer interface which is used in the newly built computer aided reserrch system for temperatute measuring in the machining with turning. This interface consists of optically-coupled linear isolation amplifier and an analog to digital (A/D) converter. It is designed for measuring of the themo- voltage that is a generated from the natural thermocouple workpiece-cutting tool. That is achived by digitalizing the value of the thermo-voltage in data which is transmitted to the personal computer. The interface realization is a result of the research activity of the faculty of Mechanical Engineering and the Faculty of Electrical Engineering in Skopje.
[en] The paper shows part of the results obtained from the investigation of joining by braze welding of heat resisting materials. The joining was effected on parts of the high-alloy heat resisting steel CH.4973 (X10CrAl18) and the sintered heat reasisting metal material WNiFe95.The samples were lapped brazed in vertical position, in the electrical resistance furnace with the filler Rolot 603 (L-CuZn40). The quality of the lapped- brazed joints was established with metallographic examinations. Analysis of the structure of the joint and the changes in the structure of the basic material was made. Also, a microhardness measuring was effected by the Vicker's method.
[en] Geomagnetic field is vector sum of causes deep in the Earth's interior and their influence can be felt in the whole Earth. There are sources of magnetic fields which are characterized for larger regions and local anomalous geomagnetic fields. When selecting the location of base station, regions where local geomagnetic anomalies are present, should be avoided, with aim to receive measured results which gives the geomagnetic field characteristic for that region. The territory of the Republic of Macedonia has complex relief, and also has complex geological structure and these features have high influence on the regional geomagnetic field. Bearing in mind the complex relief and geological structure, strict procedure of geomagnetic field observations were conducted for every selected location for repeat station. Maps from the measurements in 2004 are also presented in this paper. (Author)
[en] A survey was carried out to determine the activity concentration and distribution of 40K and gross beta activity in the soil from the city of Kavadartsi, Republic of Macedonia, and its environs. A total of 45 surface soil samples were collected from evenly distributed sampling sites over an area of 360 km2. The activity concentrations of 40K were measured using a high purity germanium (HPGe) gamma-ray detector, while the gross beta activity measurements were made using a low background gas-flow proportional counter. The obtained values for the activity concentrations of 40K were found to be in the range of 286±6 and 801±12 Bq/kg with an average value of 545±118 Bq/kg. The gross beta activities varied between 438±21 and 1052±36 Bq/kg, with an average value of 681±146 Bq/kg. These values allowed the determination of the elemental concentrations of potassium as well as the air absorbed gamma dose rate, which were found to range from 0.92±0.02 to 2.56±0.04% and from 11.9±0.1 to 33.4±0.5 nGy/h, respectively. The mean values of these parameters were 1.74±0.37% and 22.8±4.9 nGy/h. All obtained values fall within the worldwide range as reported in the literature. A strong correlation between the content of potassium in the soils and their geological origin was observed. (Author)
[en] Macedonia is one of the rare countries in the world without absolutely any development in renewable energies application during the recent 20 years. According to the absence of any development strategy or development program, it looks that such a situation shall follow during the coming period, too. Taking into account that the country took define obligations to the E C for increasing the participation of RES in the state energy balance, one can conclude that probably the reason is that some governmental institution came to a conclusion that such a development is not economically feasible, or that it is of marginal importance in the frame of present negative situation with energy supply of the country. A summary of elements of the present situation and long term consequences of such a relation is made in the paper, and the possible positive economical, ecological and technological/technical effects of its change. As illustration, results of a Study for definition of the Strategy for development of a poor region, based on wider introduction of renewable energies application are given. (Author)
[en] The history of bio-fuels/bio-diesel is more political and economical than it is technological. The technology of the production is the same as it was 200 years ago. The economy closed the usage of bio-fuels in the middies of the 20 Th century and put it back on the agenda of the world economy at the beginning of the 21 st century. With price of more then 70 US$ per barrel of grudge oil, production and usage of bio-fuels becomes more economical category rather than political and ecological. If we, additionally, add secondary, yet nowadays very important factors, as ecological protection, recycling the emission of poisonous gasses, exploitation of agro sector, then the reincarnation of bio-fuels is very interesting, and for Macedonia a potentially strategic category. The basics of the biography is to follow in the article paying special attention on the characteristics, standards, production, processing and usage of the bio-diesel fuel as well as the blended B20 and B5. (Author)