10,091 research outputs found
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
Direct Measurement of Coating Thermal Noise in Optical Resonators
The best measurements of space and time currently possible (e.g.
gravitational wave detectors and optical reference cavities) rely on optical
resonators, and are ultimately limited by thermally induced fluctuations in the
reflective coatings which form the resonator. We present measurements of
coating thermal noise in the audio band and show that for a standard ion beam
sputtered coating, the power spectrum of the noise does not have the expected
power-law behavior
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
Debates y tutorĂas como herramientas de aprendizaje para alumnos de ciencias: análisis de la integraciĂłn curricular de recursos del campus virtual
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
La Cartografia en els ordes religiosos a l'època moderna : l'atles de les provĂncies del Carmel Descalç
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
Did Men Taste and Civilization Save the stage? Theatre-going in Rotterdam, 1860-1916, A Statistical Analysis of Ticket Sales
A General Approach to Optomechanical Parametric Instabilities
We present a simple feedback description of parametric instabilities which
can be applied to a variety of optical systems. Parametric instabilities are of
particular interest to the field of gravitational-wave interferometry where
high mechanical quality factors and a large amount of stored optical power have
the potential for instability. In our use of Advanced LIGO as an example
application, we find that parametric instabilities, if left unaddressed,
present a potential threat to the stability of high-power operation
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