Nonsingular recursion formulas for third-body perturbations in mean vectorial elements

The description of the long-term dynamics of highly elliptic orbits under third-body perturbations may require an expansion of the disturbing function in series of the semi-major axes ratio up to higher orders. To avoid dealing with long series in trigonometric functions, we refer the motion to the apsidal frame and efficiently remove the short-period effects of this expansion in vectorial form up to an arbitrary order. We then provide the variation equations of the two fundamental vectors of the Keplerian motion by analogous vectorial recurrences, which are free from singularities and take a compact form useful for the numerical propagation of the flow in mean elements.

Determination of Elements in Indoor Dust at Residential Buildings Nearby a Quarry Site

Fifteen residence houses at different distances from a nearby limestone quarry were chosen to determine the concentration of elements in an indoor dust study. The samples were collected using a brush and a plastic dust pan. The elements concentrations were determined by wet digestion method with analysis using inductively coupled plasma–optical emission spectrometer (ICP-OES). The results show that the mean elements concentrations in residences houses were in the range 7.96 - 21.19, 0.21 – 0.83, 1.29 – 4.57, 0.14 – 0.26, 0.01 – 0.04 and 0.01 – 0.03 mgkg-1 for Ca, Mg, Fe, Ni, Pb and Zn respectively. The elements concentration in the investigated residential buildings areas were followed the order Ca > Fe > Mg > Zn > Ni > Pb. The evaluation of the elements contamination status of the indoor dust was carried out by using the geoaccumulation index (Igeo). Geoaccumulation index (Igeo) reveal that indoor dust of residential buildings was strongly polluted (Igeo > 5) with Ca, Mg and Fe.

N-Word Licensing

The paper, conducted within the framework of the Minimalist Program (Chomsky 1995), considers aspects of the licensing relation which obtains between Negation (Neg) and N-words in Amazigh. By N-words, I mean elements like ‘ħtta+NP’ (no-one), which are licensed by Neg. The paper shows that the Neg-N-word relation in this language is one of feature checking, with Neg-features present on the N-word requiring to be paired with corresponding features on the functional head Neg prior to Spell-Out in the position they occupy, i.e. base generated in the c-command domain of Neg. It provides further evidence for the analysis of N-words from Moroccan Arabic, one which argues for a different view of feature checking/licensing from that proposed in Chomsky 1995.

On J2 short-term orbit predictions in terms of KS elements

Sharma’s singularity-free analytical theory for the short-term orbital motion of satellites in terms of KS elements in closed form in eccentricity with Earth’s zonal harmonic term J2, is improved by using King-Hele’s expression for the radial distance ‘r’ which includes the effect of J2, and is suitable for low eccentricity orbits. Numerical experimentation with four test cases with perigee altitude of 200 km and eccentricity varying from 0.01 to 0.3 for different inclinations is carried out. It is found that the orbital elements computed with the analytical expressions in a single step during half a revolution match very well with numerically integrated values and show significant improvement over the earlier theory. The solution can be effectively used for computation of mean elements for near-Earth orbits, where the short-term orbit perturbations due to J2 play most important role. The theory will be very useful in computing the state vectors during the coast phase of rocket trajectories and flight algorithms for on-board implementation.

On the Combination of Self-Consistent and Geometric Mean Elements for the Calculation of the Elastic Properties of Textured Multi-Phase Samples

After a review of the commonly used methods to describe the elastic properties of textured polycrystals an algorithm is explained that combines elements of a geometric mean and of a generalized self-consistent approach.