TWO STEP CURRENT INCREASES IN GLOW DISCHARGE DEVELOPMENT IN NEON FILLED DIODE AT 4 mbar

Abstract. The results are presented of investigating temporal and spatial development of electrical glow discharge in a neo

Merenje nagiba kod gravitacionih betonskih brana primenom instrumenta tiltmetar

The measurement of inclination on gravity concrete dams using the instrument tiltmeter is described and discussed with special reference on obtained results on the dam 'Đerdap 2' acquired in the three years period. Tiltmetar way of operation is presented both through physical principle of vibrating wire sensors and through described design of the instrument. The influence of the temperature on the measurement of the slope is specially emphasized and presented through temperature correction. Processing the results of real inclination measurements on the dam 'Đerdap 2' with and without temperature correction showed the significant difference. Statistical analysis of measurement data consisted of performed regression analysis and forming of corresponding series with the expected measurement values depending on environmental conditions. At the end we give a summary conclusion on the instrument, the influence of temperature on the measurement and statistical model.U ovom radu prikazuje se način merenja nagiba kod gravitacionih betonskih brana primenom instrumenta tiltmetar, teorijski i preko opisa praktičnih merenja na brani 'Đerdap 2'. U prvom delu se objašnjava princip na kojem radi instrument tiltmetar i način na koji se vrši merenje nagiba primenom ovog instrumenta. Uticaj temperature na merenje nagiba je posebno razmatran kroz uvođenje temperaturske korekcije. U drugom delu se prikazuje obrada rezultata realnih merenja nagiba na jednom od instrumenata na brani 'Đerdap 2' sa i bez temperaturske korekcije. U trećem delu se prikazuje statistička obrada podataka merenja, u okviru koje se vrši regresiona analiza rezultata merenja i formiraju odgovarajuće serije sa očekivanim vrednostima merenja u zavisnosti od spoljašnjih uslova. Na kraju daje se sumarni zaključak o instrumentu, uticaju temperture na merenje i statistički model

Actual contamination of the Danube and Sava Rivers at Belgrade (2013)

This study was focussed on a comprehensive investigation on the state of pollution of the Danube and Sava Rivers in the region of Belgrade. Different complementary analytical approaches were employed covering both i) organic contaminants in the river water by target analyses of hormones and neonicotinoids as well as non-target screening analyses and ii) heavy metals in the sediments. Finally, some common water quality parameters were analysed. The overall state of pollution is on a moderate level. Bulk parameters did not reveal any unusual observations. Moreover, quantification of preselected organic contaminants did not indicate to elevated pollution. More significant contaminations were registered for chromium, nickel, zinc and partially copper in sediments with values above the target values according to Serbian regulations. Lastly, non-target screening analysis revealed a wider spectrum of organic contaminants comprising pharmaceuticals, technical additives, personal care products and pesticides. The study presented a comprehensive view on the state of pollution of the Sava and Danube Rivers and is the base for setting up further monitoring programs. As a superior outcome, it was illustrated how different chemical analyses can result in different assessments of the river quality. A comparison of target and non-target analyses pointed to potential misinterpretation of the real state of pollution

Correlative relations for defining the rock deformability

In the framework of geotechnical investigations of the rock mass at the partition site MHE Bočac 2 (BiH), Jelašnica dams on the same river in southern Serbia and nine partition sites of hydroelectric power plants on the river Ibar, detailed geotechnical investigations of the rock mass were carried out. They included exploration drilling with the definition of quasihomogenic zones within the drilled core, determination of RQD for each separated quasi-chemical zone, dilatometric tests in each well, seismic ventilation between exploratory wells or seismic carotid, core testing by the Point Load method and laboratory tests of the single-axial strength of the samples. By connecting the results of the one-axial strength, the velocity of the elastic waves and the quality of the rockl mass (RMR), i.e. these indirect data for defining the deformability of the rock masses with the obtained results of in situation deformability testing, with the results of dilatometric tests, the analysis of correlation bonds is carried out which is applied in engineering geological or geotechnical practice. As is known, in engineering practice, the following correlations are used to define the deformation module: D = f(RMR); D= f(RMR,σci); D= f(Vp) i D = f(Vp, σci). After the analysis, a correlation was applied which included all three indirect data and it gave the closest data for defining the deformability of the rock mass

TWO STEP CURRENT INCREASES IN GLOW DISCHARGE DEVELOPMENT IN NEON FILLED DIODE AT 4 mbar UDC 537.52; 533.9

Abstract. The results are presented of investigating temporal and spatial development of electrical glow discharge in a neon filled tube under 4mbar pressure. Linear increasing voltage (at 5 V/s increasing voltage rate) is applied to the gas diode. Time dependence of 585.2 nm line light emitted from negative glow is observed from various positions in the diode during formation of electrical discharge. The results show that the development of glow discharge starts in the gap, and propagates to the cathode and in the space around and behind the cathode. An unexpected two-step current rise is found. In the stationary regime, most of the emitted light occupied the cathode carrier rod. This indicates the position where the secondary electron emission is intensive. It corresponds to the second step in the current increase app. 3 ms after the breakdown has already taken place. It is assumed that this step originates from different surface characteristics of the rode material. The analysis of time dependencies of the current and light from the negative glow, from different positions in the gas diode, suggests that the observation of deexcitation processes in gas can be used for determination of early discharge formative processes, as well as processes that lead to the stationary regime in the gas diode tube

An inverse correlation between TNF alpha serum levels and heart rate variability in patients with heart failure

Background: Recent evidence indicates that chronic heart failure (CHF) is accompanied by both activation of the immune system and autonomic imbalance. There is a growing body of evidence that increased levels of proinflammatory cytokines and other inflammatory markers have important roles as mediators of disease progression and markers of mortality in patients with CHF. Objective: The aim of this study was to investigate connection between autonomic imbalance [obtained by analysis of heart rate variability (HRV)] and activation of the immune system [as measured by serum levels of tumor necrosis factor (TNF)-α] in patients with chronic heart failure. Materials and methods: This cross-sectional study included 21 patients with CHF and 8 age- and gender-matched healthy control subjects. We assessed HRV by 24-hour electrocardiographic Holter monitoring and measured serum levels of TNF-α using an enzyme-linked immunosorbent assay. Clinical assessment and echocardiography were also performed. Results: There was an inverse correlation between serum level of TNF-α and a time-domain parameter of HRV - SDNN (r= -0.542, p< 0.05). A similar result was found for HRV triangular index, a geometric measure of HRV (r= -0.556; p< 0.05). The correlation was stronger for subjects with a diabetes mellitus, females, and TNFA2 allele carriers (an A at position -308A). The pNN50, indirect marker of cardiac vagal activity, was not significantly associated with serum concentration of TNF-α. Conclusions: In conclusion, the results of the present study indicate that increased serum TNF-α level is significantly associated with reduced HRV indices, suggesting that activation of the immune system in patients with CHF is closely related to autonomic imbalance. © 2013 Japanese College of Cardiology