Tile processing

K. S. Hikncr has devised n, process depending on ihe vellow colour developed when oitral reacts with. iie/ i-phenvlcno-diamine. Tile process 13 best carried out as iollowa —... 

The product of the reaction after liquefaction separates into two layers, one an aqueous layer and the other a hydrocarbon layer containing diphenyl and the unchanged benzene. The latter mixture is separated by distilling off the benzene from the diphenyl and returning it to tile process. The diphenyl which is obtained in this way as the result of a single distillation is in a relatively pure state. 

These reductionist definitions of life are not meant to imply that tile processes or living organisms are simplistic or any the less interesting. A similar definition of physics and chemistry might be "the study of the interactions of matter and energy." None of these definitions hints at the fascination of some of the problems presented by these branches of science. 

Tile processes of the ciliary body are highly vascularized and arc the. sites of aqueous humour fonnation. The ciliary epithelial celts, which contain ATPa.se ttnd carbonic anhydrase. absorb Na selectively from the stroma and transpoit it into the intercellular clefts, which open only on the aqueous humour side. I hc hyperosmolality in the clefts causes water How from the stroma, producing a continuous How of aqticou.s. Tlie ciliary epithelium is leaky, allowing signiticam passive liltration, and up to 30% of aqueous may be formed by ulirati It ration. 

Assumption It is assumed that there is a backup plan in place for servicing the orbiter thermal tiles in case the tile processing robot has a mechanical failure and that the same backup measures can be used in the event the robot is out of commission due to other reasons. 

The high-level system hazards that might be derived from the accidents defined for the NASA thermal tile processing robot in section 7.1 might be ... 

The process of safety-guided design and the use of STPA to support it is illustrated here with the design of an experimental Space Shuttle robotic Thermal Tile Processing System (TIPS) based on a design created for a research project at CMU [57]. 

Hazard analysis using STPA will identify application-specific safety design constraints that must be enforced by the control algorithm. For the thermal-tile processing robot, a safety constraint identified above is that the manipulator arm must never be extended if the stabilizer legs are not fully extended. Causal analysis (step 2 of STPA) can identify specific causes for the constraint to be violated and design features can be created to eliminate or control them. 

Consider the mobile tile-processing robot at the beginning of this chapter. The mobile base may be designed to allow manually retracting the stabilizer legs if an emergency occurs while the robot is servicing the tiles and the robot must be physically moved out of the way. When the robot is restarted, the controller may assume... 

A final type of mode is the operating mode of the controlled process. For example, the mobile thermal tile processing robot may be in a moving mode (between work areas) or in a work mode (in a work area and servicing tiles, during which time it may be controlled by a different controller). The value of this mode may determine whether various operations—for example, extending the stabilizer legs or the manipulator arm—are safe. 

---