[sae-aadl] 2013-01-23 Error annex questions

[Myron Hecht]

Hello Peter, Brian
 
>1) An occurrence probability property indicates the probability with which
the entity occurs, with which the property is associated. For example, as a
property associated with an error source and optionally an error type token
it indicates the probability with which a component is an error source. 
 
Perhaps I'm having problems with the term "occurrence probability".  In
section E.8;1, note 12 on page 46.  It does speak about an occurrence
probability, but I thought of this is the probability of going to one state
or the other when there is a branch (fixed_probability).  I didn't think of
it as a "distribution", i.e., Poisson, Weibull, etc.
 
>e.g., as AADL model or as a Petrinet
 
 
This leads to the question about the token.  The time it stays in any one
place (whether a success or failure) is determined by the distribution.
There is a duration which seems to apply but not

  _____  

From: Peter Feiler [mailto:phf at sei.cmu.edu] 
Sent: Tuesday, February 05, 2013 1:03 AM
To: Myron Hecht; Bruce Lewis External
Cc: sae-aadl at lists.sei.cmu.edu; 'Don Ward'; 'Boydston Alex K AMRDEC'; 'Hall
Brendan \(MN65\'; 'Mike Whalen'; 'Silvia Abrahao'; 'Jean-Pierre Talpin';
'Emilio Insfran'; 'John Hatcliff'; 'May Michael J Dr OSD ATL'; 'Preston John
CIV (US'; nbrock at draper.com
Subject: RE: 2013-01-23 Error annex questions



Hi Myron,

 

Regarding E8 occurrence:

I have defined a property to express this probability distribution using a
record.

(1)   An occurrence probability property indicates the probability with
which the entity occurs, with which the property is associated. For example,
as a property associated with an error source and optionally an error type
token it indicates the probability with which a component is an error
source. 

OccurrenceProbability : record (
   ProbabilityValue : aadlreal;
   Distribution : EMV2::Distribution;
   ) 
 
Distribution : type enumeration (Poisson,Fixed);

 

I could have done it as  Occurrence: aadlreal units (poisson, fixed =>
poisson *1) applies to (all);

Using poisson or fixed as units literals requires a conversion factor as
shown.

 

The concept of a type token is useful in the context of an instance model,
e.g., as AADL model or as a Petrinet. In the context of AADL a type token
represents an error event instance or an error propagation instance. 

In the context of a representation such as Petrinet, the type token would
represent a (colored) token.

 

Peter

 

From: Myron Hecht [mailto:myron.hecht at sbcglobal.net] 
Sent: Tuesday, February 05, 2013 8:44 AM
To: Peter Feiler; Bruce Lewis External
Cc: sae-aadl at lists.sei.cmu.edu; 'Don Ward'; 'Boydston Alex K AMRDEC'; 'Hall
Brendan \(MN65\'; 'Mike Whalen'; 'Silvia Abrahao'; 'Jean-Pierre Talpin';
'Emilio Insfran'; 'John Hatcliff'; 'May Michael J Dr OSD ATL'; 'Preston John
CIV (US'; nbrock at draper.com
Subject: 2013-01-23 Error annex questions

 

Hello Peter, Bruce, et. al.

Good morning all

 

First of all, thanks for the continuing improvment on the error annex.  I
hope to be successful in making contact via Skype and LIve Meeting at 2:30
Valencia time (5:30 AM Pacifc Time).  However, in the interim, I have four
questions (which could be interpreted as comments):

 

Section E.5:  Error type tokens:  The text says it is a token is an instance
of a type, but it's not clear to me how they are used or why they are
necessary.  An example might help.

 

Section E.8: 

 

1. I couldn't find the concept of stochastic distributions for  as
occurrence properties for error events in state machines (e.g., 

Fail: error event {Occurrence => poisson lambda  };  This concept is
extremely important for quantitative modeling (note that it is related to
but distinct from the notion of a duration and branch probability).  Did I
miss something?

 

2.  Error states can be working or non-working.  Can more properties be
specified (e.g., "hazardous", etc.)?

 

3.  As was the case in section E.5, I'm afraid I don't understand the role
of tokens and how they are to be used in state machine model definitions (as
opposed to how the models are analyzed).

 

I apologize for the lateness of these remarks, but I hope they are correct
and useful nonetheless.

 

Regards

 

 

Myron Hecht

 

 

 

  

 

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