Broad spectral line and continuum variabilities in QSO spectra induced by microlensing of diffusive massive substructure

We investigate the variability of the continuum and broad lines in QSO spectra (particularly in the H$\beta$ line and continuum at $\lambda$ 5100 \AA ) caused by microlensing of a diffuse massive structure (like an open star cluster). We modeled the continuum and line emitting region and simulate a lensing event by a star cluster located in an intervening galaxy. Such a type of microlensing event can have a significant influence on magnification and centroid shift of the broad lines and continuum source. We explore relationships between the continuum and broad line flux variability during the microlensing event.Comment: 19 pages, 11 figure

Uncertainty of the wheel-rail angle of attack measurements using laser based wayside system

Ugao naletanja točka na šinu je značajan parametar dodira točak-šina. Zajedno sa silama koje nastaju pri tom dodiru, služi za ocenu dinamičkog ponašanja šinskog vozila pri prolasku kroz krivinu. U ovom radu je analizirana merna nesigurnost rezultata merenja specijalnim laserskim sistemom konstruisanim za merenje ugla naletanja točka na šinu, ističući značaj teorijskog pristupa pri izboru odgovarajućeg mernog principa i pri identifikaciji svih uticajnih parametara. Razmatran je i uticaj pravilnog postavljanja i pozicioniranja sistema na koloseku na rezultate merenja. Kako bi se ocenio kvalitet sprovedene analize, u radu su prikazani neki od rezultata merenja ovim uređajem i njihovo poređenje sa rezultatima dobijenim simulacijom, primenom specijalizovanog softverskog paketa VAMPIRE Pro. PR Projekat Ministarstva nauke Republike Srbije, br. TR 35006 i br. TR 35045.The angle of attack is an important wheel-rail contact parameter. Together with wheel-rail contact forces it serves for estimation of the rail vehicle curving performances. This paper analyses measurement uncertainty of the specially designed laser system for measurements of the wheel-rail angle of attack, with emphasis on the importance of the theoretical approach for selection of the appropriate measuring principle and for identifying all influential factors. The influence of the correct installation of the system on results is also considered. In order to evaluate quality of the analysis, some measurement results are presented and compared with the results of multibody system (MBS) simulation using specialized computer package VAMPIRE Pro

Specific aspects of the rail vehicle pass-by noise measurement

Actual European legislative (NOI TSI) urges for quitter rail vehicles requiring obligatory assessment of noise emitted by rail vehicles within vehicle approval procedure. After survey of different rail vehicle noise emission scenarios, this paper discusses more in detail specifics of the pass-by noise measurement. The requirements of the measurement procedure from applicable standards are presented and discussed on the example of the tank wagon pass-by tests. Under several parameters that can influence measurement, for vehicle approval is important to measure and check if the most influencing parameters related to track lies in specified limits. If so, the measured noise emission level mainly represents the vehicle contribution and allows comparability to noise emission measurement of other vehicles. Two main track characteristics have to be measured and assessed: acoustical rail roughness and track decay rate. In the paper are presented both measurements that are more demanding than the noise emission measurement itself

Осврт на испитивања кочнице Божић – 9 деценија касније

У току 1927. и 1928. године, под надзором Међународне железничке уније обављена су испитивања у циљу одобравања кочнице Божић за примену на возилима у међународном железничком саобраћају. Она су довела до светских патената, производње и коришћења те кочнице на великom броjу шинских возила, од којих су нека са Божић кочницом у саобраћају и данас. У раду су приказани најзанимљивији делови из извештаја о испитивањима. Оцењени су постигнути резултати и јединствени домет у историји железничког машинства Србије

Influence of head wind on the braking distance of single railway vehicle

Train stopping distance during brake application is influenced by the brake system performance, longitudinal running resistance and presence of wind and its direction. This paper deals with influence of the wind conditions on the results of slip brake tests. The influence is more expressed in the case of single vehicles tests and less expressed for the trains. The tests with and without presence of head wind were performed on the tank car type Zacns. Depending on wind speed, measured stopping distances may differ significantly. Opposite from head wind, tail wind increases stopping distance and should be considered when calculating safety margin and setting service train speed depending on the wind conditions. The results may also serve for further analyses of aerodynamic characteristics of railway vehicles and for verification of numerical simulations

Influence of measurement method and data processing on the results of brake performance test

In order to determine the brake weight of rail vehicles, brake perfomance test has to be perfomed. This test shall be conducted in accordance with the UIC 544-1. This regulation defines the necessary conditions and required quantities that shall be measured (speed, stopping distances, pressure etc.), but does not specify measuring method and all details about data processing. This paper presents possible influences on the results when using different speed measurement techniques or data processing details

Comparative analysis of the results of theoretical and experimental studies of freight wagon Sdggmrss-twin

This paper presents a comparative analysis based on the results from static strength calculation of wagon body, series Sdggmrss-twin, and on the results from the real wagon test. The verification of results from calculations and tests and their comparison was mandatory for client's commissioning of the wagon by notified body. Calculations based on the finite elements method were carried out in the Department of Railway Engineering at Technical University of Sofia. Experimental studies on real wagon construction were conducted at the facilities of Bulgarian National Transport Research Institute by testing team from Laboratory of rail vehicles at University of Belgrade. It was found that the obtained static stress results are similar, which proves that the proposed models are appropriate and they can help to solve a wide range of issues, for example those related to lightweight design of railway vehicles

Design specificity of Eams-z self-propelled wagon

Self-propelled wagon Eams-Z inteded for bulk material transportation provides enhancement in railway infrastructure construction and maintenance. Its main advantage is possibility of manipulation along tracks and construction material discharging without use of locomotive. Thus this car saves energy, human resources, and shortens the time of transportation and unloading. The car has two crates with the possibility of side and frontal inclining using hydraulic cylinders. These cylinders provide controlled and precise unloading of cargo on 3 sides without need of any extra man or machine power. Power pack, consisting of Iveco engine, hydro transmission and two small wheels without flange is positioned in the middle of the car between the bogies. In the self-propelled regime wheels lower down to rails providing traction force needed for wagon manipulation. This car type requires special attention during design and calculations in order to achieve safe manipulation in all regimes

Comparative analysis of the results of theoretical and experimental studies of freight wagon Sdggmrss-twin

This paper presents a comparative analysis based on the results from static strength calculation of wagon body, series Sdggmrss-twin, and on the results from the real wagon test. The verification of results from calculations and tests and their comparison was mandatory for client's commissioning of the wagon by notified body. Calculations based on the finite elements method were carried out in the Department of Railway Engineering at Technical University of Sofia. Experimental studies on real wagon construction were conducted at the facilities of Bulgarian National Transport Research Institute by testing team from Laboratory of rail vehicles at University of Belgrade. It was found that the obtained static stress results are similar, which proves that the proposed models are appropriate and they can help to solve a wide range of issues, for example those related to lightweight design of railway vehicles