Calcium sulfate an unusual property: when mixed with water at normal (ambient) temperatures, it quickly reverts chemically to the preferred dihydrate form, while physically "setting" to form a rigid and relatively strong gypsum crystal lattice: This reaction is exothermic and is responsible for the ease with which gypsum can be cast into various shapes including sheets (for drywall), sticks (for blackboard chalk), and molds (to immobilize broken bones, or for metal casting). Mixed with polymers, it has been used as a bone repair cement. Small amounts of calcined gypsum are added to earth to create strong structures directly from cast earth, an
Blackboard (design pattern) component; it generally takes the form of a complex scheduler that makes use of a set of domain-specific heuristics to rate the relevance of executable knowledge sources. Usage-domains include: The blackboard pattern provides effective solutions for designing and implementing complex systems where heterogeneous modules have to be dynamically combined to solve a problem. This provides non-functional properties such as: The blackboard pattern allows multiple processes to work closer together on separate threads, polling and reacting when necessary. An example of the Blackboard pattern has been provided by Microsoft. https://social.technet.microsoft.com/wiki/contents/articles/13461.blackboard-design-pattern-a-practical-example-radar-defense-system.aspx Blackboard (design pattern) In software engineering, the blackboard pattern is a