Based on the triaxial testing machine and discrete element method, the effects of embedded crack on rock fragmentation are investigated in laboratory tests and a series of numerical investigations are conducted on the...Based on the triaxial testing machine and discrete element method, the effects of embedded crack on rock fragmentation are investigated in laboratory tests and a series of numerical investigations are conducted on the effects of discontinuities on cutting characteristics and cutting efficiency. In laboratory tests, five propagation patterns of radial cracks are observed. And in the numerical tests, firstly, it is similar to laboratory tests that cracks ahead of cutters mainly initiate from the crushed zone, and some minor cracks will initiate from joints. The cracks initiating from crushed zones will run through the thinner joints while they will be held back by thick joints. Cracks tend to propagate towards the tips of embedded cracks, and minor cracks will initiate from the tips of embedded cracks, which may result in the decrease of specific area, and disturbing layers play as ‘screens', which will prevent cracks from developing greatly. The peak penetration forces, the consumed energy in the penetration process and the uniaxial compression strength will decrease with the increase of discontinuities. The existence of discontinuities will result in the decrease of the cutting efficiency when the spacing between cutters is 70 mm. Some modifications should be made to improve the efficiency when the rocks containing groups of discontinuities are encountered.展开更多
The aim of presented study was to determine the behavioural response of precopulatory pairs of Gammarus tigrinus exposed to the 17α-ethinylestradiol （EE2）. It was hypothesized that 17α-ethinylestradiol would incre...The aim of presented study was to determine the behavioural response of precopulatory pairs of Gammarus tigrinus exposed to the 17α-ethinylestradiol （EE2）. It was hypothesized that 17α-ethinylestradiol would increase the time needed for a male to re-capture a female. Hypothesis was tested in a laboratory with 20 precopula pairs exposed to different treatment conditions. Paired animals were exposed to two different compound concentrations of 50 ng·L-1 and 500 ng·L-1. The control and solvent control was artificial sea water and artificial sea water with ethanol （the diluent for EE2）. The couples were tested several times under different experimental treatments. The obtained results indicate that EE2 affects the precopulatory mate guarding behaviour of Gammarus tigrinus. EE2 in concentration of 50 ng·L-1 and 500 ng·L-1 prolonged the time needed for re-pairing. However, relative to the controls only EE2 in concentration of 500 ng·L-1 significantly prolonged the time needed for male-female re-coupling. In summary, EE2 affects the reproductive behaviour of Gammarus tigrinus.展开更多
The quality variety wines which are produced in specified regions of Slovakia are mostly watched category of wine in European Union. Quality of the measurement for appropriate parameter in wine sample is given by unce...The quality variety wines which are produced in specified regions of Slovakia are mostly watched category of wine in European Union. Quality of the measurement for appropriate parameter in wine sample is given by uncertainty. Therefore, protocol of analysis has to have an uncertainty of measurement and should be made in accredited laboratory. In Slovakia, there are six wine growing regions （Tokaj, east Slovakia region, south Slovakia region, middle Slovakia region, Nitriansky region and Little-Carpathian region） where the quality wines with protected designation of origin are produced. Central Controlling and Testing Institute in Agriculture in Bratislava is a state organization, which has an accredited laboratory for testing wine products before introduction into the market. This article presents the results of the authors＇ measurements in proficiency testing FAPAS （food analysis performance assessment scheme） which were organized by Central Science Laboratory in York （England） in 2011. The authors add also interlaboratory comparison in 2012 between Slovak accredited laboratories. The results show very good agreement. Quality control in the wine sector presents very important feature in the market, therefore, using certified reference materials and checking the accredited laboratories with interlaboratory comparisons is very helpful. Testing of wine in the authors＇ laboratory is performed by EN ISO/IEC： 17025. The results show that z-score lies not outside the range ±2 and this is a chance that the authors＇ results are actually acceptable.展开更多
基金Project(2013CB035401) supported by the National Basic Research Program of ChinaProject(51174228) supported by the National Natural Science Foundation of China+1 种基金Project(71380100003) supported by Hunan Provincial Innovation Foundation for Postgraduate,ChinaProject(201304) supported by Open Research Fund of Hunan Province Key Laboratory of Safe Mining Techniques of Coal Mines(Hunan University of Science and Technology),China
文摘Based on the triaxial testing machine and discrete element method, the effects of embedded crack on rock fragmentation are investigated in laboratory tests and a series of numerical investigations are conducted on the effects of discontinuities on cutting characteristics and cutting efficiency. In laboratory tests, five propagation patterns of radial cracks are observed. And in the numerical tests, firstly, it is similar to laboratory tests that cracks ahead of cutters mainly initiate from the crushed zone, and some minor cracks will initiate from joints. The cracks initiating from crushed zones will run through the thinner joints while they will be held back by thick joints. Cracks tend to propagate towards the tips of embedded cracks, and minor cracks will initiate from the tips of embedded cracks, which may result in the decrease of specific area, and disturbing layers play as ‘screens', which will prevent cracks from developing greatly. The peak penetration forces, the consumed energy in the penetration process and the uniaxial compression strength will decrease with the increase of discontinuities. The existence of discontinuities will result in the decrease of the cutting efficiency when the spacing between cutters is 70 mm. Some modifications should be made to improve the efficiency when the rocks containing groups of discontinuities are encountered.
文摘The aim of presented study was to determine the behavioural response of precopulatory pairs of Gammarus tigrinus exposed to the 17α-ethinylestradiol （EE2）. It was hypothesized that 17α-ethinylestradiol would increase the time needed for a male to re-capture a female. Hypothesis was tested in a laboratory with 20 precopula pairs exposed to different treatment conditions. Paired animals were exposed to two different compound concentrations of 50 ng·L-1 and 500 ng·L-1. The control and solvent control was artificial sea water and artificial sea water with ethanol （the diluent for EE2）. The couples were tested several times under different experimental treatments. The obtained results indicate that EE2 affects the precopulatory mate guarding behaviour of Gammarus tigrinus. EE2 in concentration of 50 ng·L-1 and 500 ng·L-1 prolonged the time needed for re-pairing. However, relative to the controls only EE2 in concentration of 500 ng·L-1 significantly prolonged the time needed for male-female re-coupling. In summary, EE2 affects the reproductive behaviour of Gammarus tigrinus.
文摘The quality variety wines which are produced in specified regions of Slovakia are mostly watched category of wine in European Union. Quality of the measurement for appropriate parameter in wine sample is given by uncertainty. Therefore, protocol of analysis has to have an uncertainty of measurement and should be made in accredited laboratory. In Slovakia, there are six wine growing regions （Tokaj, east Slovakia region, south Slovakia region, middle Slovakia region, Nitriansky region and Little-Carpathian region） where the quality wines with protected designation of origin are produced. Central Controlling and Testing Institute in Agriculture in Bratislava is a state organization, which has an accredited laboratory for testing wine products before introduction into the market. This article presents the results of the authors＇ measurements in proficiency testing FAPAS （food analysis performance assessment scheme） which were organized by Central Science Laboratory in York （England） in 2011. The authors add also interlaboratory comparison in 2012 between Slovak accredited laboratories. The results show very good agreement. Quality control in the wine sector presents very important feature in the market, therefore, using certified reference materials and checking the accredited laboratories with interlaboratory comparisons is very helpful. Testing of wine in the authors＇ laboratory is performed by EN ISO/IEC： 17025. The results show that z-score lies not outside the range ±2 and this is a chance that the authors＇ results are actually acceptable.
