Solar walls for high-performance buildings

Passive solar design can reduce building energy demand for heating, cooling and ventilation, while also contributing to the comfort, well-being and productivity of the building’s occupants. The successful application of passive solar features, such as solar walls, requires a good understanding of the factors influencing their energy performance and a correct assessment of this performance during the design process. This paper discusses some basic design strategies for successful application of solar walls and the factors with the most significant impact on their efficiency. It summarizes the principle results and findings of an experimental study, based on dynamic simulations and test site measurements. The energy performance of various configurations of unvented solar walls was investigated in different climatic conditions. The outcomes of the dynamic simulations were used to develop a simplified quasisteady-state model, which can be used for approximate evaluation of the heat gains and heat losses through an unvented solar wall on a monthly basis. The model is compatible with the monthly method of EN ISO 13790.This work has been supported by The National Science Fund of Bulgaria under projects number ДУНК-01/3 (DUNK-01/3) and ДФНИ Е 02/17 (DFNI E 02/17)

The large-scale ionised outflow of CH Cygni

HST and ground-based [OII} and [NII] images obtained from 1996 to 1999 reveal the existence of a ionised optical nebula around the symbiotic binary CH Cyg extending out to 5000 A.U. from the central stars. The observed velocity range of the nebula, derived from long-slit echelle spectra, is of 130 km/s. In spite of its complex appearence, the velocity data show that the basic morphology of the inner regions of the optical nebula is that of a bipolar (or conical) outflow extending nearly along the plane of the sky out to some 2000 A.U. from the centre. Even if the extension of this bipolar outflow and its position angle are consistent with those of the radio jet produced in 1984 (extrapolated to the time of our optical imagery), no obvious counterpart is visible of the original, dense radio bullets ejected by the system. We speculate that the optical bipolar outflow might be the remannt of the interaction of the bullets with a relatively dense circumstellar medium.Comment: 8 text pages + 3 figures (jpeg). ApJ in press. For a full PostScript version with figures inline see ftp://ftp.ll.iac.es/pub/research/preprints/PP252001.ps.g

Radiation Environment In Earth-Moon Space: Results From RADOM Experiment Onboard Chandrayaan-1

The Radiation Monitor (RADOM) payload is a miniature dosimeter-spectrometer onboard Chandrayaan-1 mission for monitoring the local radiation environment in near-Earth space and in lunar space. RADOM measured the total absorbed dose and spectrum of the deposited energy from high energy particles in near-Earth space, en-route and in lunar orbit. RADOM was the first experiment to be switched on soon after the launch of Chandrayaan-1 and was operational till the end of the mission. This paper summarizes the observations carried out by RADOM during the entire life time of the Chandrayaan-1 mission and some the salient results.Comment: Accepted for publication in Advances in Geoscience

Lithium in the Symbiotic Mira V407 Cyg

We report an identification of the lithium resonance doublet LiI 6708A in the spectrum of V407 Cyg, a symbiotic Mira with a pulsation period of about 745 days. The resolution of the spectra used was R~18500 and the measured equivalent width of the line is ~0.34A. It is suggested that the lithium enrichment is due to hot bottom burning in the intermediate mass AGB variable, although other possible origins cannot be totally ruled out. In contrast to lithium-rich AGB stars in the Magellanic clouds, ZrO 5551A, 6474A absorption bands were not found in the spectrum of V407Cyg. These are the bands used to classify the S-type stars at low-resolution. Although we identified weak ZrO 5718A, 6412A these are not visible in the low-resolution spectra, and we therefore classify the Mira in V407 Cyg as an M type. This, together with other published work, suggests lithium enrichment can precede the third dredge up of s-process enriched material in galactic AGB stars.Comment: 4 pages, 2 figures, to be published in MNRA

Analytical response time estimation in parallel relational database systems

Techniques for performance estimation in parallel database systems are well established for parameters such as throughput, bottlenecks and resource utilisation. However, response time estimation is a complex activity which is difficult to predict and has attracted research for a number of years. Simulation is one option for predicting response time but this is a costly process. Analytical modelling is a less expensive option but requires approximations and assumptions about the queueing networks built up in real parallel database machines which are often questionable and few of the papers on analytical approaches are backed by results from validation against real machines. This paper describes a new analytical approach for response time estimation that is based on a detailed study of different approaches and assumptions. The approach has been validated against two commercial parallel DBMSs running on actual parallel machines and is shown to produce acceptable accuracy

Merging Galaxies in the SDSS EDR

We present a new catalog of merging galaxies obtained through an automated systematic search routine. The 1479 new pairs of merging galaxies were found in approximately 462 sq deg of the Sloan Digital Sky Survey Early Data Release (SDSS EDR; Stoughton et al. 2002) photometric data, and the pair catalog is complete for galaxies in the magnitude range 16.0 <= g* <= 20. The selection algorithm, implementing a variation on the original Karachentsev (1972) criteria, proved to be very efficient and fast. Merging galaxies were selected such that the inter-galaxy separations were less than the sum of the component galaxies' radii. We discuss the characteristics of the sample in terms of completeness, pair separation, and the Holmberg effect. We also present an online atlas of images for the SDSS EDR pairs obtained using the corrected frames from the SDSS EDR database. The atlas images also include the relevant data for each pair member. This catalog will be useful for conducting studies of the general characteristics of merging galaxies, their environments, and their component galaxies. The redshifts for a subset of the interacting and merging galaxies and the distribution of angular sizes for these systems indicate the SDSS provides a much deeper sample than almost any other wide-area catalog to date.Comment: 58 pages, which includes 15 figures and 6 tables. Figures 2, 8, 9, 10, 11, 13, and 14 are provided as JPEG files. For online atlas, see http://home.fnal.gov/~sallam/MergePair/ . Accepted for publication in A

Discovery of a bipolar and highly variable mass outflow from the symbiotic binary StHa 190

A highly and rapidly variable bipolar mass outflow from StHa 190 has been discovered, the first time in a yellow symbiotic star. Permitted emission lines are flanked by symmetrical jet features and multi-component P-Cyg profiles, with velocities up to 300 km/sec. Given the high orbital inclination of the binary, if the jets leave the system nearly perpendicular to the orbital plane, the de-projected velocity equals or exceeds the escape velocity (1000 km/sec). StHa190 looks quite peculiar in many other respects: the hot component is an O-type sub-dwarf without an accretion disk or a veiling nebular continuum and the cool component is a G7 III star rotating at a spectacular 105 km/sec unseen by a large margin in field G giants.Comment: Letter to the Editor, Astron.Astrophys, in pres