Antenna phase pattern measurements at millimeter wave frequencies using the differential phase method with only one power meter

The differential phase measurement method has been improved to need the use of only one power meter instead of three power meters. This enables accurate antenna phase pattern measurements with a simplified set-up, accompanied by the reduction in cost. All advantages of the differential phase measurement method are still also available, e.g. there is no need to phase lock oscillators or to use rotary joints. The measurement results for an antenna at 110 GHz are presented. A good agreement with earlier data was obtained.     

The biological leaching of an auriferous pyrite ore

The oxidation of an auriferous pyrite ore sample was evaluated in biological leaching experiments for subsequent gold recovery via cyanidation. In batch cultures, organisms derived from the mine site oxidized pyrite and ferrous iron at pH values as low as pH 0.6. The recovery of gold was variable in shake flask experiments. In stirred tank bioreactor leaching, gold recovery was proportional to the extent of iron dissolution by bioleaching. The leaching of arsenic from the sample was also directly proportional to iron dissolution.     

Machine learning in continuous casting of steel: a state-of-the-art survey

Journal of Intelligent Manufacturing - Continuous casting is the most important route for the production of steel today. Due to the physical, mechanical, and chemical components involved in the...     

Adaptive optical array receivers for detection of surface acoustic waves

Adaptive interferometric detection systems based on two-wave mixing in photorefractive crystals have been configured as distributed optical receivers. The spatial distribution of the detection laser power on the sample surface is controlled by use of phase gratings and amplitude masks. The responses of point, line, array, and chirped optical receivers to propagating surface acoustic waves (SAW's) are discussed theoretically and demonstrated experimentally. It is shown that by use of different object beam footprints it is possible to configure adaptive holographic SAW receivers that are either broadband or narrow band and that are preferentially sensitive to SAW's propagating in given directions. The receivers also allow for the distribution of laser power over the sample, eliminating the excessive heating or surface damage that can occur in some materials when high power, point-focused, detection lasers are used.     

Schrifttumsberichte

Ohne Zusammenfassung     

Test beam results of Current Injected Detectors (CID) irradiated up to 5×10 1 MeV neq/cm

Two full size strip detectors were investigated in this study: one with p⁺ strips (p⁺/n⁻/n⁺) and another with n⁺ strips (n⁺/p⁻/p⁺). Both detectors, are made of magnetic Czochralski silicon (MCz-Si) and irradiated to S-LHC fluencies, were tested with 225 GeV muon beam in the CERN H2 area. The Current Injected Detector (CID) sensors were operated in a cooling box capable of providing a −53 °C temperature. Results indicate a relative charge collection efficiency (CCE) at 5×10¹⁵ n_eq/cm² above 30% in irradiated p⁺/n⁻/n⁺ CID detector at 600 V bias voltage. The signal to noise ratio of this CID module was about eight and a forward current of 30 μA was needed for detector biasing. In standard reverse bias, the same detector could not provide a sufficiently large signal for particle tracking purposes. A p-type (n⁺/p⁻/p⁺) sensor was irradiated to a fluence of 2×10¹⁵ n_eq/cm² and measured under the same test beam conditions. According to the theory of CIDs developed by the CERN RD39 Collaboration, this detector module could be biased up to only 230 V due to the low irradiation fluence. The CCE at 230 V was 35% in CID operation and 20% when reverse biased.     

Method for testing reflector antennas at THz frequencies

The possibilities of applying far-field, near-field, and compact-range techniques to reflector antennas in the THz frequency range are discussed. Other methods, such as defocusing and combining of the mechanical-reflector-surface measurements and the feed-horn-radiation patterns, are also discussed. A recently introduced hologram type of compact range is described. It may be concluded from the analysis of the different methods that the far-field method can be discarded due to atmospheric effects. The near-field method remains a possibility. However, an expensive, high-quality, moving stage is needed, and phase errors caused by flexible cables have to be dealt with. In some cases, a defocusing method, to bring the far field closer, may prove to be practical. Technically, the most-feasible and least-expensive method appears to be the hologram type of compact range. In this method, a planar-amplitude hologram is used to form the required plane wave. The hologram is inexpensive to manufacture, and it is also less sensitive to surface-accuracy errors than a reflector     

Ferrihydrite in water wells and bacterial enrichment cultures

The chemical and mineralogical composition of Fe(III)-precipitates formed in water wells and laboratory cultures was examined. Ferrihydrite, a poorly ordered Fe(III)-oxide of bulk formula 5Fe₂O₃ · 9H₂O, was detected by X-ray diffraction analysis in all samples. The crystallinity varied from one sample to another. Fe was the only major element detected by energy-dispersive X-ray spectrometry; several other elements were present at minor levels reflecting the chemical composition of the medium. The results suggest that the biologically-catalyzed iron encrustation of water wells begins with the initial formation of ferrihydrite.     

Validation of ceiling jet flows in a large corridor with vents using the CFD code JASMINE

A field model code, JASMINE, has been adopted to calculate ceiling jet flows caused by plumes from unsteady fire sources in a large corridor. The idealized fast- and medium-fire energy release rates, obeying thet ² law for fire growth, were used. The effects of vents were studied by simulating three different configurations: a centrally located vent—that is, a vent directly above the fire source; an eccentrically located vent; and no vent. The results were compared with recent large-scale experiments conducted at the Swedish National Testing and Research Institute (SP) and with results from the computer program LAVENT. Some calculated sprinkler temperatures with three different RTI values are also presented.The present JASMINE simulations agree reasonably well with measured ceiling temperatures and velocities in large-scale tests. In general, the calculated ceiling jet temperatures are slightly overestimated and the velocities slightly underestimated. Also, the layer thicknesses calculated by JASMINE are somewhat thinner than those measured. The ceiling jet theory and present LAVENT results predict very thin layer thicknesses. However, these theories are only valid when wall effects are eliminated. From the present study it can be concluded that CFD models are generally more accurate when used to predict confined and unconfined flows.