A ground test measurement system for the shuttle entry air data system

The Ground Test Measurement System (GTMS) for determining vacuum decay leak rate within the orifice tubing assembly of SEADS is described. The system can also monitor the absolute pressure in the tubing assembly under certain conditions. The GTMS determines leak rate by measuring vacuum-pressure decay which can be converted into leakage flow rate. Results of performance testing and operation of the GTMS are given

VIGS en die Suid-Afrikaanse ekonomiese en bestuurswêreld - Enkele perspektiewe

There is no doubt anymore that AIDS as a disease has the potential to become a very serious issue in the South African social, political, demographic and economic environment. AIDS will have macro-economic as well as micro-business implications. At macro-level (without the influence of AIDS) decision-makers already anticipate and plan for a • shortage in housing for blacks; • shortage in employment opportunities; • high level of unemployment; • uncontrollable urbanisation; and a • lack of educational infrastructure. Burning issues for decision-makers and managers will be • who will be the worker tomorrow? • who will be the manager? • will there be sufficient manpower resources? • what would a training strate& took like ? • in what ways will production and productivity be managed? • in what ways will sound labour relations be created and maintained? Although a great many decision-makers and managers still have a sceptical view and perception regarding AIDS, it is certain that it will affect the entire spectrum of life. Managers should proactively plan for the implications of AIDS on business, and if projections do not realise as darkly, it could be seen and accepted as a "bonus

Enkele aspekte van die suid-afrikaanse bevolking- en arbeidsituasie

Vanweë tegnologiese ontwikkelings wat die kommunikasie tussen lande bykans vervolmaak, is dit so dat geen land sigself geisoleerd kan beskou of probeer hou van die res van die wêreld nie. Hierdie verbondenheid tussen lande word intenser op die terrein van bevolkings en bevolkingsgroei vanweë die feit dat lande se bevolkingsdigtheid1) in baie gevalle groot verskil toon. Omdat bevol- kingstoenames een van die vemaamste bedreigings vir die mens-dom, asook vir wêreldvrede, inhou, vorm dit een van die mees delikate aangeleenthede waarmee landsowerhede hulself besig hou en gaan dit in die toekoms waarskynlik groot wrywing op intemasionaJe vlak veroorsaak. Die wrywing tussen lande vind normaalweg gestalte in gekamoefleerde geskilpunte oor „diver- se” sake maar word basics veroorsaak deur die vrees vir oorbe- volking en gevolglike hongersnood in sy uiterste graad

Spontaneous Raman scattering for simultaneous measurements of in-cylinder species

A technique for multi-species mole fraction measurement in internal combustion engines is described. The technique is based on the spontaneous Raman scattering. It can simultaneously provide the mole fractions of several species of N-2, O-2, H2O, CO2 and fuel. Using the system, simultaneous measurement of air/fuel ratio and burnt residual gas are carried out during the mixture process in a Controlled Auto Ignition (CAI) combustion engine. The accuracy and consistency of the measured results were confirmed by the measured air fuel ratio using an exhaust gas analyzer and independently calculated mole fraction values. Measurement of species mole fractions during combustion process has also been demonstrated. It shows that the SRS can provide valuable data on this process in a CAI combustion engine

Notations and conventions in molecular spectroscopy: part 1. General spectroscopic notation

The field of Molecular Spectroscopy was surveyed in order to determine a set of conventions and symbols which are in common use in the spectroscopic literature. This document, which is Part I in a series, establishes the notations and conventions used for general spectroscopic notations and deals with quantum mechanics, quantum numbers (vibrational states, angular momentum and energy levels), spectroscopic transitions, and miscellaneous notations (e.g. spectroscopic terms). Further parts will follow, dealing inter alia with symmetry notation, permutation and permutation-inversion symmetry notation, vibration-rotation spectroscopy and electronic spectroscopy

Notations and conventions in molecular spectroscopy: part 2. Symmetry notation

The field of Molecular Spectroscopy was surveyed in order to determine a set of conventions and symbols which are in common use in the spectroscopic literature. This document, which is Part 2 in a series, establishes the notations and conventions used for the description of symmetry in rigid molecules, using the Schoenflies notation. It deals firstly with the symmetry operators of the molecular point groups (also drawing attention to the difference between symmetry operators and elements). The conventions and notations of the molecular point groups are then established, followed by those of the representations of these groups as used in molecular spectroscopy. Further parts will follow, dealing inter alia with permutation and permutation-inversion symmetry notation, vibration-rotation spectroscopy and electronic spectroscopy

6,6′-(Pyridine-2,6-di­yl)bis­(pyrrolo­[3,4-b]pyridine-5,7-dione)

The title compound, C19H9N5O4, has crystallographically imposed twofold rotational symmetry. The asymmetric unit contains one half-mol­ecule. The crystal structure is stabilized by π–π stacking of inversion-related pyrrolo­[3,4-b]pyridine rings, with a centroid–centroid distance between stacked pyridines of 3.6960 (8) Å. The dihedral angle between the central pyridine ring and the pyrrolo-pyridine side rings is 77.86 (2)° while the angle between the two side chains is 60.87 (2)°

Ices in the edge-on disk CRBR 2422.8-3423: Spitzer spectroscopy and Monte Carlo radiative transfer modeling

We present 5.2-37.2 micron spectroscopy of the edge-on circumstellar disk CRBR 2422.8-3423 obtained using the InfraRed Spectrograph (IRS) of the Spitzer Space Telescope. The IRS spectrum is combined with ground-based 3-5 micron spectroscopy to obtain a complete inventory of solid state material present along the line of sight toward the source. We model the object with a 2D axisymmetric (effectively 3D) Monte Carlo radiative transfer code. It is found that the model disk, assuming a standard flaring structure, is too warm to contain the very large observed column density of pure CO ice, but is possibly responsible for up to 50% of the water, CO2 and minor ice species. In particular the 6.85 micron band, tentatively due to NH4+, exhibits a prominent red wing, indicating a significant contribution from warm ice in the disk. It is argued that the pure CO ice is located in the dense core Oph-F in front of the source seen in the submillimeter imaging, with the CO gas in the core highly depleted. The model is used to predict which circumstances are most favourable for direct observations of ices in edge-on circumstellar disks. Ice bands will in general be deepest for inclinations similar to the disk opening angle, i.e. ~70 degrees. Due to the high optical depths of typical disk mid-planes, ice absorption bands will often probe warmer ice located in the upper layers of nearly edge-on disks. The ratios between different ice bands are found to vary by up to an order of magnitude depending on disk inclination due to radiative transfer effects caused by the 2D structure of the disk. Ratios between ice bands of the same species can therefore be used to constrain the location of the ices in a circumstellar disk. [Abstract abridged]Comment: 49 pages, accepted for publication in Ap