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

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

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

Six years of study on fast growing forest plantations catchments in the Northwest of Spain

Data on water balance in three fast growing forest plantations experimental catchments in the northwest of Spain are presented. Two watersheds are covered by Eucalyptus globulus and other is covered by Pinus pinaster. During the six years of study severa1 perturbations occurred. In 1989 two consecutives wildfires affected to one E. globulus watershed. The second fire also bumed the other eucalyptus watershed. All eucalyptus were felled since 1991 to 1992. Also 25% of the watershed area in the pine catchment was cutted in 1991. Quick changes in the hydrologycal regimen took place after these perturbations. The very fast recovering capacity after fire and cutting of Eucalyptus globulus facilitated the retum to pre-fire hydrologic parameter values within only a few years. Before perturbations occurred, nutrient balances were very conservative, and were similar among the cathments. This indicates a good performance on the part of both tree plantations. Water comsumption for pine and eucalyptus stands was very similar

The closed orbit measurement system for the CERN Antiproton Decelerator

The closed-orbit measurement system for the new Antiproton Decelerator (AD) employs 59 electrostatic pick-ups (PU). The intensity range from 2·1010 down to 107 particles poses challenging demands on the dynamic range and noise of the head amplifier. A low noiseamplifier has been developed, having an equivalent input noise of 0.6nV/√(Hz), allowing beam positions to be measured to ±0.5 mm with 5·106 particles. Two different gains take care of the large dynamic range. After amplification and multiplexing, the PU signals are fed to a network analyser, where each measurement point corresponds to one PU. The network analyser is phase locked to the RF of the AD, thus acting as a “tracking filter” instrument. An orbit measurement takes from 0.2 to 12 s depending on the IF-bandwidth of the network analyser, selected according to the beam intensity, and the precision required. At the end of the network analyser sweep the data are read via a GPIB interface and treated by a real-time task running in a VME based Power PC

A study on elasto-plastic impact friction

A purpose-built pendulum machine was used to study the oblique impact and the behaviour of the surface layers of a normalized low alloy steel subjected to the impact of hard [alpha]-alumina balls. The effect of relative tangential velocity on impulses, restitution coefficient and impact energy loss, was analysed. The morphology of the impact indentations was characterized and related to the impulses obtained. There was lip formation in the target material with ejection of a small fragile oxidized chip, at a certain critical sliding speed. The impact duration and the impulse ratio have maximum values. These values seem to be related to the critical angle of attack, common in abrasive and erosive ductile processes. The experimental results were compared with some impact models and theories.http://www.sciencedirect.com/science/article/B6V5B-3WRC3G0-4/1/41e4c5269f22928dae6bfa3fb640fd0

The OTR screen betatron matching monitor of the CERN SPS

In order to satisfy the stringent emittance requirements of LHC, betatron matching monitors, based on multiturn beam profile measurements, have been proposed for the SPS and LHC. A test monitor has been installed for evaluation in the CERN SPS first in 1996 and improved in 1997. It is based on an OTR screen and a fast beam profile acquisition system. It has been used with proton beams to assess the quality of the betatron matching from the PS to the SPS in 1998. Experience and results are presented

Adaptive optics for the LEP 2 synchrotron light monitors

The image obtained with the LEP synchrotron radiation telescopes deteriorates, giving multiple and deformed images, when the beam energy goes beyond 80 GeV at beam currents above 2 mA. This problem is due to the deformation of the light extracting beryllium mirror, by as little as 1 mm, and had been predicted at the design stage. To overcome this problem, several changes together with an adaptive optics set-up have been introduced. These essentially consist of a cylindrically deformable mirror to compensate the cylindrical deformation of the beryllium mirror and a movable detector to compensate the spherical deformation. Both components are continuously adjusted as a function of beam current and energy