Doug Kerr
Well-known member
Yesterday (2011.05.08) was my 75th birthday. In its honor, a current series of new and substantially updated technical articles is being branded the "75th birthday series".
The first two articles released under this marque do not directly concern photography. The third does, and is announced in another forum section here:
http://www.openphotographyforums.com/forums/showthread.php?p=114743#post114743
But just for general reference, I'll announce the other two here.
Principles of Steam Locomotive Valve Systems
A critical element of the reciprocating steam engine that propels a conventional steam locomotive is its valve system, whose task is to admit team under pressure to one side of the piston or the other at appropriate periods within the cycle, and vent those chambers to the atmosphere during other periods.
Complicated engineering issues govern the needed timing, under a pattern that must be varied for different stages of locomotive operation (just as we must change the transmission ratio in a motor vehicle.)
In a locomotive, it is vital that this non-trivial task be done by robust mechanisms not needing adjustment in the field. As a result we have robust continuous-motion piston-type valves, moved by clever and robust continuous-motion mechanisms, called the valve gear.
In my new technical article, "Principles of Steam Locomotive Valve Systems", I discuss this area from the standpoint of operation under a tidy mathematical model of valve motion, and then demonstrate how two important valve gear designs essentially fulfill that model.
The article is available here:
http://dougkerr.net/Pumpkin/articles/Loco_Valves.pdf
The Episcopal Civil War
The Episcopal Church, the U. S. arm of the worldwide Anglican Communion, is embroiled in a controversy—a “civil war”—so virulent as to hold the potential of schism of the denomination, or even of the Anglican Communion itself.
In my article, "The Episcopal Civil War", I summarize the principal presenting issues in this controversy, describe significant events along the way, and characterize the present state of the matter. The article has just been updated, especially to give a current summary of two major legal actions spawned by the defection of Episcopal church leaders, clergy, and congregants from The Episcopal Church.
The article is available at:
http://dougkerr.net/Pumpkin/articles/Episcopal_Civil_War.pdf
Best regards,
Doug
The first two articles released under this marque do not directly concern photography. The third does, and is announced in another forum section here:
http://www.openphotographyforums.com/forums/showthread.php?p=114743#post114743
But just for general reference, I'll announce the other two here.
Principles of Steam Locomotive Valve Systems
A critical element of the reciprocating steam engine that propels a conventional steam locomotive is its valve system, whose task is to admit team under pressure to one side of the piston or the other at appropriate periods within the cycle, and vent those chambers to the atmosphere during other periods.
Complicated engineering issues govern the needed timing, under a pattern that must be varied for different stages of locomotive operation (just as we must change the transmission ratio in a motor vehicle.)
In a locomotive, it is vital that this non-trivial task be done by robust mechanisms not needing adjustment in the field. As a result we have robust continuous-motion piston-type valves, moved by clever and robust continuous-motion mechanisms, called the valve gear.
In my new technical article, "Principles of Steam Locomotive Valve Systems", I discuss this area from the standpoint of operation under a tidy mathematical model of valve motion, and then demonstrate how two important valve gear designs essentially fulfill that model.
The article is available here:
http://dougkerr.net/Pumpkin/articles/Loco_Valves.pdf
The Episcopal Civil War
The Episcopal Church, the U. S. arm of the worldwide Anglican Communion, is embroiled in a controversy—a “civil war”—so virulent as to hold the potential of schism of the denomination, or even of the Anglican Communion itself.
In my article, "The Episcopal Civil War", I summarize the principal presenting issues in this controversy, describe significant events along the way, and characterize the present state of the matter. The article has just been updated, especially to give a current summary of two major legal actions spawned by the defection of Episcopal church leaders, clergy, and congregants from The Episcopal Church.
The article is available at:
http://dougkerr.net/Pumpkin/articles/Episcopal_Civil_War.pdf
Best regards,
Doug