Asteroid long-periodic perturbations: The second order Hamiltonian

The Hamiltonian of the second order with respect to the disturbing mass, as defined in the higher order-higher degree theory of asteroid secular perturbations by Yuasa (1973), is expressed in the heliocentric, ecliptic coordinate system. Errors found in the original paper with terms coming from the principal part of the disturbing function are removed, and corrected values of the coefficients are computed. The importance of second-order perturbations and the improvement in the accuracy of proper element determination, achieved by using the newly-obtained coefficients, are demonstrated. Finally, a table of the secular frequencies as functions of the semimajor axis is given, and compared with the analogous one by Kozai (1979).     

A visual basic spreadsheet macro for recession curve analysis

A Visual Basic program for an Excel spreadsheet was written to construct a master recession curve (MRC), using the adapted matching strip method, for recession analysis of ground water level time series. The program uses five different linear/nonlinear regression models to adjust individual recession segments to their proper positions in the MRC. The program can also be used to analyze the recession segments of other time series, such as daily stream discharge or stage. Some examples of field data from Croatia are used to illustrate the usefulness of its application.     

Stark Broadening in Compact Stars: Xe VI Lines

We will consider Stark broadening of non hydrogenic spectral lines in the impact approximation in compact stars: pre-white dwarf and white dwarf atmospheres. In order to show an example, Stark broadening parameters have been calculated, using the impact semiclassical perturbation approach for four Xe VI spectral lines. Obtained results have been used to demonstrate the influence of Stark broadening in DA and DB white dwarf atmospheres.     

On the Stark Broadening of Lu III Spectral Lines

The electron-impact widths for 27 Lu III spectral lines have been calculated by using the modified semiempirical method. Calculations have been also performed with the published relativistic Hartree-Fock oscillator strengths and additionally, with the approximate formula of Cowley. With the obtained results, the influence of Stark broadening on Lu III lines was investigated in the spectra of A-type stars. The obtained data will be included in the STARK-B database, which is part of the Virtual Atomic and Molecular Data Center – VAMDC.     

Effectiveness of tune mass damper in the reduction of the seismic response of the structure

A shaking table testing of a 16.6 t five storey steel frame structure with and tuned mass damper (TMD) named as Tuned Mass Control System (TMCS) installed at the top has been carried out in the Dynamic Testing Laboratory at the Institute of Earthquake Engineering and Engineering Seismology (IZIIS) in Skopje, Republic of Macedonia. For estimation of the effectiveness of Tuned Mass Control System (TMCS) large number of shaking table experiments have been performed. Simulating different earthquake time histories on the model structure with and without TMCS it has been demonstrated that this system is capable to reduce the responses in order from 10% to more than 50% depending on the frequency content of the seismic input and the corresponding sensitivity of the structure. Given a high quality analytical model of a structure and a dynamic absorber, a series of variant analyses have been performed within the study to investigate the effect of the individual parameters and evaluate the efficiency of the dynamic absorber. The analyses have been performed to define the effect of the location of the absorber, also, upon the dynamic behaviour of the structure in the case the absorber is installed at the different level (storey) of the structure. Comparative analysis of the structure with TMCS having optimally tuned its mechanical properties versus structure that has TMCS having the same mechanical properties as tested specimen showed that the TMCS additionally improves the structural behaviour, depending on frequency content of earthquake excitation.