The effect of the solar field reversal on the modulation of galactic cosmic rays

There is now a growing awareness that solar cycle related changes in the large-scale structure of the interplanetary magnetic field (IMF) may play an important role in the modulation of galactic cosmic rays. To date, attention focussed on two aspects of the magnetic field structure: large scale compression regions produced by fast solar wind streams and solar flares, both of which are known to vary in intensity and number over the solar cycle, and the variable warp of the heliospheric current sheet. It is suggested that another feature of the solar cycle is worthy of consideration: the field reversal itself. If the Sun reverses its polarity by simply overturning the heliospheric current sheet (northern fields migrating southward and vice-versa) then there may well be an effect on cosmic ray intensity. However, such a simple picture of solar reversal seems improbable. Observations of the solar corona suggest the existence of not one but several current sheets in the heliosphere at solar maximum. The results of a simple calculation to demonstrate that the variation in cosmic ray intensities that will result can be as large as is actually observed over the solar cycle are given

HH 1158: The lowest luminosity externally irradiated Herbig-Haro jet

We have identified a new externally irradiated Herbig-Haro (HH) jet, HH 1158, within ~2 pc of the massive OB type stars in the sigma Orionis cluster. At an Lbol ~ 0.1 Lsun, HH 1158 is the lowest luminosity irradiated HH jet identified to date in any cluster. Results from the analysis of high-resolution optical spectra indicate asymmetries in the brightness, morphology, electron density, velocity, and the mass outflow rates for the blue and red-shifted lobes. We constrain the position angle of the HH 1158 jet at 102+/-5 degree. The mass outflow rate and the mean accretion rate for HH 1158 using multiple diagnostics are estimated to be (5.2 +/- 2.6) x 10^(-10) Msun/yr and (3.0 +/- 1.0) x 10^(-10) Msun/yr, respectively. The properties for HH 1158 are notably similar to the externally irradiated HH 444 -- HH 447 jets previously identified in sigma Orionis. In particular, the morphology is such that the weaker jet beam is tilted towards the massive stars, indicating a higher extent of photo-evaporation. The high value for the Halpha/[SII] ratio is also consistent with the ratios measured in other irradiated jets, including HH 444 -- HH 447. The presence of an extended collimated jet that is bipolar and the evidence of shocked emission knots make HH 1158 the first unique case of irradiated HH jets at the very low-luminosity end, and provides an opportunity to learn the physical properties of very faint HH jet sources.Comment: Accepted in ApJ Letter

Aerodynamic spike nozzle Patent

Constructing fluid spike nozzle to eliminate heat transfer and high temperature problems inherent in physical spike

Study of Cloud Impact on Fixed Satellite Communication Link at Ku, Ka and V Bands in Nigeria

The study investigates the effect of clouds on fixed satellite communication link on earthspace path in Nigeria for 0.01 to 10% unavailability of an average year. The input data (from August 2002 to July 2009) used for the study are base on recent meteorological data measured from space by the Atmospheric Infrared Sounder satellites (AIRS). The International Telecommunication Union Radio Propagation Recommendation (ITU-RP, 2009) procedure was used for the computation of cloud attenuation statistics for each of the 37-stations for link to Nigeria Communication Satellite (NigComsat-1), for both uplink and downlink frequencies. At Ku band (12/14 GHz), cloud fade is between 0.2 to 0.55 dB, for Ka band (20/30 GHz), 0.6 to 2.4 dB and for V band (40/50 GHz) 2.0 to 6.0 dB. A Contour map of cloud attenuation at Ku, Ka and V-band for 0.01% unavailability, at 0.1 by 0.1 degree latitude and longitude for downlink and uplink to NigComsat-1 was developed. The maps show consistently that impact of cloud is generally severe in the southern part of Nigeria

Sound separation probe

Probe separates sound waves from turbulent flow pressure fluctuations in ducted airstreams by using principle that sound waves and turbulent flow pressure perturbations travel at different velocities

Satellite retrieval system

A satellite retrieval system with first and second pairs of coacting parallel bars are separately mounted in spaced parallel planes on the front of a spacecraft. The bars of one pair are at right angles to bars of the other pair, and together the two pairs of bars effect a variable aperture adapted to close around a rod extending from a second spacecraft to effect the capture of the latter

Replaceable filters and cones for flared-tubing connectors

Connector is modified by machining the cone from one end before the fitting is bored to accommodate a metallic-filament type of slip-in filter. Thus, when surface of the cone is damaged, only the cone needs replacement