Effect of silicate ions on electrode overvoltage

The influence of the addition of a silicate to a caustic solution (KOH) is studied in order to determine the degree to which silicates inhibit the corrosion of chrysotile under conditions of electrolysis at working temperatures of 100 C and above. In an alkaline solution containing various silicate concentrations, current density was increased and electrode overvoltage was measured. Results show that silicate ion concentrations in the electrolyte increase with temperature without effecting electrochemical performance up to 115 C at 700 MA/sqcm. At this point the concentration is about 0.5 g Si/100 g KOH. Beyond this limit, electrolytic performance rapidly degenerates due to severe oxidation of the electrodes

Optical properties of Southern Hemisphere aerosols: Report of the joint CSIRO/NASA study

This study was made in support of the LAWS and GLOBE programs, which aim to design a suitable Doppler lidar system for measuring global winds from a satellite. Observations were taken from 5 deg S to 45 deg S along and off the E and SE Australian coast, thus obtaining representative samples over a large latitude range. Observations were made between 0 and 6 km altitude of aerosol physical and chemical properties in situ from the CSIRO F-27 aircraft; of lidar backscatter coefficients at 10.6 micron wavelength from the F-27 aircraft; of lidar backscatter profiles at 0.694 microns at Sale, SE Australia; and of lidar backscatter profiles at 0.532 microns at Cowley Beach, NE Australia. Both calculations and observations in the free troposphere gave a backscatter coefficient of 1-2 x 10 to the -11/m/sr at 10.6 microns, although the accuracies of the instruments were marginal at this level. Equivalent figures were 2-8 x 10 to the -9/m/sr (aerosol) and 9 x 10 to the -9 to 2 x 10 to the -8/m/sr (lidar) at 0.694 microns wavelength at Sale; and 3.7 x 10 to the -9/m/sr (aerosol) and 10 to the -8 to 10 to the -7/m/sr (lidar) at 0.532 microns wavelength at Cowley Beach. The measured backscatter coefficients at 0.694 and 0.532 microns were consistently higher than the values calculated from aerosol size distributions by factors of typically 2 to 10

Haze in the Klang Valley of Malaysia

Continuous measurements of dry aerosol light scattering (Bsp) were made at two sites in the Klang Valley of Malaysia between December 1998 and December 2000. In addition 24-h PM2.5 samples were collected on a one-day-in-six cycle and the chemical composition of the aerosol was determined. Periods of excessive haze were defined as 24-h average Bsp values greater than 150 Mm-1 and these occurred on a number of occasions, between May and September 1999, during May 2000, and between July and September 2000. The evidence for smoke being a significant contributor to aerosol during periods of excessive haze is discussed and includes features of the aerosol chemistry, the diurnal cycle of Bsp, and the coincidence of forest fires on Sumatra during the southwest (SW) monsoon period, as well as transport modelling for one week of the southwest Monsoon of 2000. The study highlights that whilst transboundary smoke is a major contributor to poor visibility in the Klang Valley, smoke from fires on Peninsular Malaysia is also a contributor, and at all times, the domestic source of secondary particle production is present

A generic persistence model for CLP systems (and two useful implementations)

This paper describes a model of persistence in (C)LP languages and two different and practically very useful ways to implement this model in current systems. The fundamental idea is that persistence is a characteristic of certain dynamic predicates (Le., those which encapsulate state). The main effect of declaring a predicate persistent is that the dynamic changes made to such predicates persist from one execution to the next one. After proposing a syntax for declaring persistent predicates, a simple, file-based implementation of the concept is presented and some examples shown. An additional implementation is presented which stores persistent predicates in an external datábase. The abstraction of the concept of persistence from its implementation allows developing applications which can store their persistent predicates alternatively in files or databases with only a few simple changes to a declaration stating the location and modality used for persistent storage. The paper presents the model, the implementation approach in both the cases of using files and relational databases, a number of optimizations of the process (using information obtained from static global analysis and goal clustering), and performance results from an implementation of these ideas

Trajectory measurement of bunches ejected from the CERN PSB

The transfer line of the PS Booster(PSB) recombines beams from the 4 vertically stacked rings of the PSB and sends them to 1 of 3 possible destinations: the 26 GeV PS, ISOLDE, or the measurement line. To acquire the transverse positions of the beam, 18 electrostatic pick-ups are distributed along the lines and variable gain triple-channel amplifiers (DH, DV and S), equipped with a calibration system that operates every cycle, are mounted on each pick-up. The digitisation is achieved with 8-bit 250MHz ADC VME modules. Data treatment allows simultaneous calculations of the beam position corresponding to each ring to be made for all pick-ups on every cycle as well as allowing calibration, base-line correction and auto-ranging for optimising the resolution of the fast ADCs. Measurements are made with a resolution of 0.3 mm (full scale 33 mm) over an intensity range of 100 for a maximum of 1013 protons per ring. The data treatment is performed as a real-time task in a VME crate equipped with a Motorola MVME147 CPU board and conforms to the standard instrumentation protocol as well as the PS control system

Screens versus SEM grids for single pass measurements in SPS, LEP and LHC

When the transfer channels of the SPS and LEP were designed in the 70¹s and early 80¹s, it was foreseen to use screens to observe qualitatively the beam positions and shapes and Secondary Emission Grids and Split Foils to perform precision profile and position measurements. Foils covering the whole aperture were installed for measuring the beam intensities. The original screens were 1 mm thick, which blows up the low energy beams and limits the number of screens which can be used simultaneously. With the use of different screen materials, image acquisition hardware and processing software, the TV screens are now competing with the SEM Grids for precision measurements. The screens are simpler in construction, have a large spatial resolution, typically 105 points, and are more sensitive. The use of fast luminescent material and thin Optical Transition Radiation screens are extending the screen monitor field to bunch length and time structure measurements. Limitations of Secondary Emission Monitors and results obtained with screens with hadrons and leptons are reported. Future applications are considered