84 lines
3.9 KiB
HTML
84 lines
3.9 KiB
HTML
<html>
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<head>
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<title> The Velocity Selector </title>
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</head>
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<body>
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<h1>The Velocity Selector </h1>
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<p>
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The velocity selector is a turbine rotating at high speed. This turbine
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annihilates all neutrons which do not manage to travel through the
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turbine in a time intervall defined by the rotation speed of the turbine.
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Thus neutrons in a certain speed range (energy range) are selected. The
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distribution of neutrons is also dependent of a tilt angle between the
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rotation axis of the turbine and the neutron beam. A high speed device like
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a velocity selector has to account for gyroscopic forces when moving the
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device. In praxis this means that the selector must be stopped before the
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tilt angle can be changed. Furthermore there are forbidden areas of rotation
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speeds. In these areas the velocity selector is in destructive resonance with
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itself or its bedding. The command set for a velocity selector is defined
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below. The name of the velocity selctor object is assumed to be nvs.
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</P>
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<P>
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<DL>
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<DT>nvs rottolerance par
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<DD>Sets or requests the tolerance the rotation speed may have before an
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error is issued.
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<DT>nvs list
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<DD>Displays rotation speed and tilt angle of the velocity selctor.
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<DT>nvs add min max
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<DD>This command adds a forbiden region between min and max to the list
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of forbidden regiosn of the velocity selector. These values are usually
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configured in the configuration file.
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<DT> nvs rot = newval tilt = newval
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<DD> This command sets a new tilt angle and/or rotation speed for the
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velocity selector. Either one or both of the keywords tilt or rot may be
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given, followed by a number.
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<DT> nvs interrupt val
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<DD>Requests or sets an interrupt value. This interrupt will be issued when
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an error on this velocity selector ocurred. With a parameter a new value
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is set, without the current value is printed.
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<DT> nvs userrights val
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<DD>Requests or sets a userright value. This userright value defines
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who may drive this velocity selector. With a parameter a new value
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is set, without the current value is printed.
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<DT> nvs tilttolerance val
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<DD>Requests or sets a tilttolerance value. This parameter defines the
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permissable tolerance for the tilt motor. With a parameter a new value
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is set, without the current value is printed.
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<DT>nvs rotinterest
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<DD>Enables printing of status messages about the current state of the
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selector when it is driven.
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<DT> nvs loss
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<DD> Starts a loss current measurement on the velocity selector and prints the
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result.
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<DT>nvs forbidden
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<DD>Prints a list of forbidden speed regions for this selector.
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<DT>nvs status
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<DD>Prints a status summary of the velocity selector.
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</DL>
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</p>
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The commands described so far cover the actual handling of the velocity
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selector. During a measurement users might want to use further functions
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such as:
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<ul>
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<li> Monitor the rotation speed of the velocity selector.
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<li> Log the rotation speeds of the velocity selector.
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<li> Initiate error handling when the velocity selector fails to stay within
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a predefined tolerance of rotation speeds.
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</ul>
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Now, these are tasks usually connected with sample environment devices. Now,
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the SICS programmers have been lazy. Moreover they wanted to avoid
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duplicating code
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(and bugs). Consequently, they tricked the velocity selector to be a
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sample environment device as well. This means besides the actual velocity
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selector object (in this case called nvs) there exists another object for
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monitoring the velocity selector. The name of this device is the name of the
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velocity selector object with the string watch appended. For example if the
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velocity selector has the SICS name nvs, the monitor object will be
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nvswatch. The commands understood by the watch object are fully decribed in
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the section about <a href="samenv.htm#all">sample environment devices</a>.
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Please note, that all driving commands for the watch object have been
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disabled. Driving can only be achieved through the velocity selector object.
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</body>
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</html>
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