ODREĐIVANJE ELASTIČNE GRANICE ISKOPA KOD VELIKIH PODZEMNIH RUDARSKIH PROJEKATA

Uncertainty-based stope boundary optimization is a complex part of underground mine planning, especially in mass mining projects and notably block caving. Besides, grade variation and grade uncertainty are significant sources of error in mining projects. This paper presents a procedure to determine a resilient block-cave stope boundary considering the ore grade uncertainties. The procedure applies the floating stope algorithm, the maximum upside/minimum downside, and the value at risk for design evaluation. The floating stope algorithm is customized for block caving and is used to determine the stope boundary over some simulated grade models. The idea fits into a multi-criteria decision-making problem. Finally, the most resilient stope boundary is selected by considering several criteria and the TOPSIS method. According to the results, the resilient stope boundary covers an area where the mineable reserve is 977 Mt with an average copper grade of 0.51%.Optimizacija granica iskopa metodom temeljenom na nesigurnosti složen je dio projektiranja podzemnih rudnika, posebno u projektima masovnoga rudarenja te u metodi blokovskoga iskopa. Osim toga, varijacija u stupnju i nesigurnost sadržaja rude česti su izvori pogrešaka u rudarskim projektima. Ovaj rad predstavlja postupak za određivanje elastične granice blokovskoga iskopa uzimajući u obzir nesigurnosti sadržaja rude. Postupak primjenjuje algoritam plutajućih granica iskopa, maksimalno dobru / minimalno lošu stranu i rizičnu vrijednost za ocjenu dizajna. Algoritam plutajućih granica iskopa prilagođen je za blokovsku metodu iskopa i koristi se za određivanje granice iskopa preko određenih simuliranih stupnjevitih modela. Ideja se uklapa u višekriterijski problem odlučivanja. Konačno, odabire se najelastičnija granica iskopa uzimajući u obzir nekoliko kriterija i TOPSIS metodu. Prema rezultatima elastična granica iskopa pokriva područje gdje eksploatacijske rezerve iznose 977 Mt s prosječnim sadržajem bakra od 0,51 %

Reaction of Brassica species to Sclerotinia sclerotiorum applying inoculation techniques under controlled conditions

Oilseed rape is economically affected by stem rot caused by Sclerotinia sclerotiorum worldwide. Glucosinolates are the specific secondary metabolites of Brassica plants that appear in different profiles of each species. Their hydrolysis products have biocidal activity and may play a role in resistance against plant pathogenic fungi. The resistance of oilseed rape (Brassica napus) cultivars and two other Brassica species (B. nigra and Sinapis alba) was evaluated employing leaf disc inoculation, and oxalic acid and fungal inoculums on leaves of intact plants under controlled conditions. By using leaf disc inoculation, three plant ages were used to compare their reactions against the pathogen. No significant differences between genotypes were observed in this method. However, results demonstrated significant differences in main effects of wounding and plant age. The two intact plant inoculation techniques (oxalic acid and fungal mycelium) resulted in significant differences between genotypes in reaction to the disease. Furthermore, the oxalic acid assay followed the same pattern as fungal inoculations. Among the oilseed rape cultivars, AV-Sapphire and AG-Castle were the most resistant and susceptible genotypes, respectively. Brassica species differed significantly in their reaction to disease, in both wounded and non-wounded leaves with fungal mycelium inoculation and oxalic acid. Overall, non-significant differences between Brassica genotypes showed the unreliability of the leaf disc assay, whereas leaf inoculation of intact plants by means of either oxalic acid or fungal mycelium demonstrated significant differences in lesion size among Brassica cultivars and species

Estimation of mining time-span to improve the solution time in long-term production planning

Long-term production planning in open-pit mines is a precedence-constraint knapsack problem. A spatial representation of the mining region (called the block-model) is the primary input of mine planning models. One should note that as the number of blocks and periods to be planned increases, the number of decision variables increases. This paper presents a fast yet straightforward algorithm to reduce binary variables in open-pit mine production planning models. The algorithm considers mining capacity, processing capacity, and pit deepening rate to estimate the time span within which a block is mineable. This paper applies the algorithm in 12 different cases. The number of blocks varies from 1000 to 240000, and the mining periods range from 6 to 30 years. According to the results, this algorithm is helpful for problem size reduction

Association between 25-hydroxyvitamin D levels and the carotid intima-media thickness

Background: There are insufficient data on the association between the serum level of vitamin D and the carotid intima-media thickness (CIMT). The aim of this study was to investigate the association between the level of serum 25-hydroxyvitamin D and the CIMT. Methods: This cross-sectional study recruited 341 patients. The level of 25-hydroxyvitamin D was measured with radioimmunoassay, and the CIMT was measured with color Doppler ultrasound. Results: The mean serum level of 25-hydroxyvitamin D was 14.88±14.63 ng/mL in the patients with a significant carotid artery involvement and 17.02±13.56 ng/mL in those without a carotid involvement, with the difference between the 2 groups constituting statistical significance (P=0.034). The prevalence rate of vitamin D deficiency in those with and without a carotid involvement was 88.6 and 74.4; the rate was significantly higher in the former group (P=0.039). Conclusions: Our study confirmed recent suggestions regarding the association between vitamin D deficiency and the progress of atherosclerosis in carotid arteries as CIMT. © 2019, Iranian Heart Association. All rights reserved