Central Data System Design for Scientific Solar Probes

Scientific solar probes (such as Pioneer) are aimed at mapping the radiation and particle fields of the solar corona. The central data system design must accorrn:nodate different instrument complements as mission assignments and emphasis change. Telemetry channel capacity is restricted by extreme range and practical limitations on antenna gain and transmitter power. Adaptive data sampling and telemetry formats, and sophisticated processing algorithms, which the experimenters have the option to use or not, are required to make efficient use of the available telemetry channel capacity. The central data system requires a stored program for mission-to-mission flexibility, and ultra-reliability to meet mission effectiveness standards. Ultra-reliability is obtained through the pooling of logical units in such a way that the failure of one unit does not disable the computer. A diagnostic program exercises the on-board data system. An on-ground computer program isolates the fault from telemetry information and reprograms the on- board computer around the fault via the command link. A system simulation model for the central data system of a scientific space probe has been designed and programmed. The goal is to define the basic and ancillary services that the central computer can provide the experimenters . Development of the simulation program has forced the designer to consider all aspects of the system in minute detail. The instrument complement assumed for the simulation consists of a triaxial magnetometer, cosmic ray telescope, neutron detector, radio propagation experiment, plasma probe, micrometeorite detector, and a VLF wave-particle experiment. Engineering data inputs are simulated and processed by the simulation program

Monitoring Subsurface Drainage Flow at Remote Locations

Laboratory evaluations and field results are presented for a slotted weir used to measure discharge from subsurface drains. The head–discharge curve for the vertical slot is a simple power function with an exponent of 1.5. There was excellent agreement (r2 \u3e 0.99 and 1:1 slope) between predicted and observed discharge in laboratory testing of 12 test weirs representing five slot widths. The primary advantages of the vertical slot weir are its simplicity, ease of maintenance, and ability to measure small flow rates. Disadvantages include a tendency for the slot to close a small amount over time as a result of creep when using a PVC pipe and the possibility for material to become clogged in the slot. The use of a spacer in the slot eliminated the tendency for the slot to close