Dragan Nikolić

Deconvolution of plasma broadened non-hydrogenic neutral atom lines

Abstract A method for the deconvolution of non-hydrogenic neutral atom lines using Marquardt–Levenberg algorithm is presented. Algorithm for application of this method is also described. The application of this method to isolated and overlapping neutral argon lines is given as an example.

Simple method for deconvolution of a Gaussian and a plasma broadened spectral line profile jA,R(χ)

Abstract Computation of the convolution integral of a Gaussian and the Stark-broadened jA,R(χ) profile has been carried out and the results are expressed in a form suitable for the analysis of spectral line profiles.

A simple method for bremsstrahlung spectra reconstruction from transmission measurements

A new method for evaluation of bremsstrahlung spectra from transmission measurements has been developed. In this method some very well known facts relating to thick target bremsstrahlung spectra are a priori included in the calculation procedure. Some characteristics of the method are preliminarily illustrated on a 6 MV therapy linear accelerator.

Intermediate Hamiltonian to avoid intruder state problems for doubly excited states

An intermediate Hamiltonian method suitable for many-body perturbation theory calculations on doubly excited states is presented. The method is designed to be able to avoid the intruder states that often prevent convergence, especially for doubly excited states. The feasibility of the procedure is demonstrated on a few doubly excited states in helium for which convergence cannot be achieved with conventional all-order many-body methods.

Line shape study of neutral argon lines in plasma of an atmospheric pressure wall stabilized argon arc

We report results of the measurement of the Stark parameters for several visible neutral argon lines. For this study wall stabilized arc is used as a plasma source. Electron densities of (0.74–2.9)×1022xa0m−3 are determined from the width of the Hβ line and electron temperatures of (9280–10xa0750)xa0K are deduced from plasma composition data. Precision technique for spectral line shape recordings is applied. The deconvolution procedure for asymmetric line profiles is used to determine the Stark broadening parameters from experimental line shapes. The results are compared with theoretical and other experimental data.

Optimization of UHPFRC beams subjected to bending using genetic algorithms

AbstractUltra high performance fibre reinforced concrete (UHPFRC) is cementitious composite with very high strength, and when compared with ordinary concrete it is a more superior material both in terms of its mechanical properties and its durability. In order to predict the behaviour of UHPFRC beams, first of all, experiments were carried out to investigate the mechanical properties of composites containing 2% and 4% of steel fibres. Following this, four beams of 2 m in length were tested by subjecting to four point bending. Two beams contained only micro steel fibres, while the remaining two contained conventional steel bar reinforcement. On the basis of experimental studies and recommendations by the AFGC for UHPC, the behaviour of the beams was modelled and optimization was carried out using genetic algorithms (GA) according to the criterion of minimum price. In this paper, the prices of individual UHPFRC beams are also shown in comparison with beams, which contain steel bars or prestressed reinforcement.

MAGNEZIJ SULFAT KAO ADJUVANS U ANESTEZIJI KOD BOLESNIKA S POVIŠENIM KRVNIM TLAKOM

There is limited evidence showing that elevated arterial blood pressure in surgicalnpatients may be associated with increased perioperative risk; however, cardiovascular instability frequentlynoccurs during anesthesia. The most commonly used anesthetic agents, both intravenous andninhalation ones, produce a decrease in arterial blood pressure. Magnesium, acting as a natural calcium-channelnblocker, induces direct and indirect vasodilatation, thus playing a role in the treatment of arterialnhypertension. In this research, we assessed the effects of magnesium sulfate on cardiovascularnstability in patients undergoing diverse planned surgical procedures (abdominal, orthopedic, urology)nunder general balanced anesthesia, who were diagnosed with arterial hypertension grade 1 and 2. Thenresearch encompassed 100 patients of both sexes, aged from 20 to 65. Immediately before inductionnof anesthesia with propofol, the patients in the experimental group (50 study subjects) received 30 mg/nkg bolus dose and magnesium sulfate infusion at 10 mg/kg/h, whereas the subjects in the controlngroup (50 patients) were administered normal saline. Anesthesia was achieved and maintained withnsevoflurane, fentanyl and rocuronium. The hemodynamic variables of mean arterial pressure and heartnrate were measured every five minutes, starting immediately before magnesium infusion. Statisticalnanalysis of the categorized values of mean arterial pressure and heart rate revealed a statistically significant between-group ndifference at 60th and 90th minute of anesthesia. In conclusion, magnesiumnsulfate as an adjuvant to anesthesia in patients with arterial hypertension reduces hemodynamicnchanges during anesthesia.

High resolution studies of electron-ion recombination

The formation of atoms by recombination of free electrons with ions is a fundamental process and plays a central role in astro-physical and fusion plasmas. It can be seen as time-inverse photo-ionization, auto-ionization, or electron-impact ionization. Here, we show how these processes can be measured with cooler-storage rings, such as CRYRING at MSL, with very high accuracy. The status of theoretical modeling is briefly reviewed and anomalies are uncovered. We discuss some examples of recombination for ions where strong dielectronic recombination resonances occur. With cooler-storage rings, these resonances can today be measured with meV accuracy, and from the spectra of the dielectronic resonances, very accurate values for energy splittings and resonance strengths are derived. These allow crucial tests of relativistic, correlation, and QED effects in these systems.

Asymmetry and Shifts Interdependence in Stark Profiles

The asymmetry of the Stark profile of the Balmer Hβ line of Hydrogen in dense plasmas is analyzed with respect to its dependence on reference points and electronic shifts of the individual Stark components. The strong interdependence of the asymmetry and the shifts is found experimentally and theoretically.