This paper proposes the importance of multiple instrumentation and data ........

This paper proposes the importance of multiple instrumentation and data source (triangulation) in a needs analysis. Various data gathering methods developed in assessing learners? English language needs are reviewed. The justification of employing more than a single data gathering method and data source in a needs analysis is also presented by examining the strengths and weaknesses of each method and evaluating previous needs analyses carried out in some Asian countries. Highlights are then given to the methodology mostly implemented in assessing English needs in Indonesia and a recommendation is addressed to further studies on learners?s needs in Indonesia

Manufacturer and designer of groundwater Monitoring Instrumentation including water level indicator, well water data logging, water level logger, water level gauges, water level sensor, groundwater data logger by Heron Instruments in Ontario, Canada.

0008-5472

DA - 19960122 IS - 1073-449X (Print) LA - eng PT - Guideline PT - Journal Article PT - Practice Guideline RN - 630-08-0 (Carbon Monoxide) SB - AIM SB - IM

The Large Plasma Device at the University of California, Los Angeles has recently been upgraded. The plasma is now 18 m long (the device is 22 m long) and is designed to produce a 0.36 T axial magnetic field. Its plasma source has also been upgraded, incorporating a 1 m square heater, a 72 cm diameter cathode and anode, and associated heat shields and reflectors. The barium oxide coated cathode is heated to 750 $\,^\circ$C and can produce plasmas of diameters up to 0.9 m diameter (depending on the magnetic field configuration), and densities up to 7×1012 cm?3 with a spatial uniformity of $\pm$10%.

The large plasma research device (LAPD), a large, linear plasma research device designed to study space plasma processes, has been constructed at UCLA over the past four years. The LAPD has a 0.5×0.5 m2 oxide-coated cathode as a source which produces a 10-m-long plasma column with densities up to the mid 1012/cm3 range. The linear machine is surrounded by a set of 68 magnet coils which can generate an axial magnetic field of up to 3000 G. The vacuum chamber has 128 radial ports to ensure excellent access for probes and antennas. An internal probe drive capable of moving a set of probes to any position within the plasma column is described in a companion paper. This machine is a scientific instrument in its own right and was designed to be versatile enough to study a large variety of phenomena. The techniques employed in the design and construction are sufficiently useful to be discussed here so that others can benefit from our experience.

We present the design of a modular, robust, high-current switch for controlling discharge current in the large plasma device (LAPD) at UCLA. As developed, 10 insulated gate bipolar transistor units are connected in parallel to provide 24 kA current-carrying capacity. Associated snubber and protection circuits are described in detail. The switch is typically operated at a 1 Hz repetition rate, with up to a 2% duty cycle. It has proven to be quite reliable, to date having pulsed approximately 5×107 times, with a net throughput of about 2 billion Coulombs. This type of switch not only has an application in such a plasma source, but can also be used to switch large currents for a variety of applications. The design is modular and the switch can be made smaller or larger depending on the desired current rating