In the summer of 1999, we had used the bottom two layers of 3T to provide autonomous control for a single subsystem--a second-generation biological water processor--during a 450-day, 24-hour-a-day, 7-day-a week test. Then in January 2000, the Advanced Water Research Group received ALS funding for the year-long IWRS test, involving four advanced water-recovery subsystems (Bonasso 2001) (see Advanced Water Recovery System sidebar).BuildupUsing 3T allowed us to develop the control for the IWRS in a modular fashion in two ways. First, moving from bottom to top (figure 4), each layer has its own data structures, timing constraints, and development tools that allow for parallel development of the software. Thus, we were able to develop skills sets based on the evolving hardware specifications and simultaneously develop the sequencer procedures. Early on, as the water research team developed the design for each subsystem, one part of the 3T team wrote the sequencer procedures for each subsystem in the RAPS language (which, in turn, is written in Lisp) (1) using virtual skills, that is, Lisp skills connected to a Lisp simulation of the expected hardware. A virtual simulation of, say, the reverse-osmosis subsystem could then be shown on a laptop to the WRS engineers and the control design refined in an iterative process even before the actual hardware was available. The primary result of this process was a set of skill specifications for each subsystem (figure 5).

The ministry report said, ''''These findings prove that the overgrowth of diatom plankton has resulted in a reduction in the nutrient salts in the sea, thereby causing the poor growth of ''nori'' seaweed.'''' Diatom plankton is a type of photo plankton. The number of creatures inhabiting the seabed, such as shellfish and shrimps, were small at many surveyed points, it said.''''There is the possibility that the fall in the number of these seabed creatures which consume the nutrient salts has resulted in the overabundance of nutrient salts in seawaters, thus causing the overgrowth of photo plankton,'''' the ministry said.The reclamation project has been under way since 1986 to create 1,840 hectares of farmland. The eight lock gates were shut in 1997.

There is also a new header height sensing system for rigid platforms. The new mechanical header height sensing system for 600 Rigid Platforms is a major improvement for rigid platform operation. This system automatically maintains a consistent cut height from 4- to 14-inches over uneven field terrain.Cutting capacity has also been improved on the 600 Series Platforms.7020 tractorsDeere has also introduced three new models of 7020 tractors designed with new styling, cabs, frames, and engines for greater productivity, reliability and value. The tractors are the 7720 rated at 140 PTO hp, the 7820 at 155-hp and the 7920 which features 170-hp.

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