Ca ii λλ3934, 3969 absorbers, which are likely to be a subset of damped Lyman α systems, are the most dusty quasar absorbers known, with an order of magnitude more extinction in E(B−V) than other absorption systems. There is also evidence that Ca ii absorbers trace galaxies with more ongoing star-formation than the average quasar absorber. Despite this, relatively little is known in detail abou...

We investigate the evolution and the statistical properties of the Ly α absorbers of the intergalactic medium (IGM) in the largely unexplored redshift range z = 0.5−1.9. We use high-resolution (R ≥ 30 000) UV (STIS) and optical (VLT/UVES and Keck/HIRES) spectra of nine bright quasars with z em < 1.94. The Ly α lines detected in the lines of sight (LOS) towards these quasars are evaluated with a...

Numerical optimisations were conducted to reduce the noise levels inside the payload bay of a rocket by using vibration and acoustic absorbers attached to the fairing walls. The vibration absorbers act in both translational and rotational axes. The acoustic absorbers were modelled as simplified Helmholtz resonators. A Finite Element model of the vibro-acoustic system was created in ANSYS and th...

We present a detailed study of the circumstellar medium (CSM) around the progenitor stars of longduration γ-ray bursts (GRBs) at redshift z > 1.5. We establish a statistical sample of five GRB spectra for which the data were collected and analyzed with no prior knowledge of the line-of-sight properties, and carry out a systematic search of Wolf-Rayet wind signatures, as represented by blue-shif...

The red quasar 3C212 (z = 1.049) is one of the most distant and most luminous AGN which has shown evidence of an X-ray warm absorber. In order to further investigate this unusual quasar, we used Chandra/ACIS-S to observe 3C212 for 19.5 ksec, resulting in a net detection of ∼ 4000 counts. The Chandra data confirm the presence of an excess absorbing column NH ≈ 4 × 10 21 cm at the quasar redshift...

Conceptual innovation in mechanical engineering design has been extremely challenging compared to the wide applications of automated design systems in digital circuits. This paper presents an automated methodology for open-ended synthesis of mechanical vibration absorbers based on genetic programming (GP) and bond graphs (GPBG). It is shown that our automated design system can automatically evo...

We present a detailed model for the ionized absorbing gas evident in the 900 ksec Chandra HETGS spectrum of NGC 3783. The analysis was carried out with PHASE, a new tool designed to model X-ray and UV absorption features in ionized plasmas. The 0.5-10 keV intrinsic continuum of the source is well represented by a single power law (Γ = 1.53) and a soft black-body component (kT ∼ 0.1 keV). The sp...

We present a detailed model for the ionized absorbing gas evident in the 900 ksec Chandra HETGS spectrum of NGC 3783. The analysis was carried out with PHASE, a new tool designed to model X-ray and UV absorption features in ionized plasmas. The 0.5-10 keV intrinsic continuum of the source is well represented by a single power law (Γ = 1.53) and a soft black-body component (kT ∼ 0.1 keV). The sp...

Spectrally-selective solar absorbers harvest solar energy in the form of heat. Solar absorbers using cermet-based coatings demonstrate a high absorptance of the solar spectrum and a low emittance in the infrared (IR) regime. Extensive work has been done to optimize cermet-based solar absorbers to achieve high performance by exploring different cermet (ceramic-metal composite) materials and film...