Global qualitative flow-path modeling for local state determination in simulation and analysis

• US 5,732,192 A
• Filed: 11/30/1994
• Issued: 03/24/1998
• Est. Priority Date: 11/30/1994
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Malin, Jane T., Fleming, Land D.
• Primary Examiner(s): Hafiz, Tariq R.
• Assistant Examiner(s): Smith, Jeffrey S.
• Application Number:
  US08/346,793
• Time in Patent Office: 1,210 Days
• Field of Search: 395/10, 395/51, 364/578
• US Class Current: 703/2
• CPC Class Codes: G06F 30/367 Design verification, e.g. using simulation, simulation program with integrated circuit emphasis [SPICE], direct methods or relaxation methods

Abstract

For qualitative modeling and analysis, a general qualitative abstraction of power transmission variables (flow and effort) for elements of flow paths includes information on resistance, net flow, permissible directions of flow and qualitative potential. Each type of component model has flow-related variables and an associated internal flow map, connected into an overall flow network of the system. For storage devices, the implicit power transfer to the environment is represented by "virtual" circuits that include an environmental junction. A heterogeneous aggregation method simplifies the path structure. A method determines global flow-path changes during dynamic simulation and analysis, and identifies corresponding local flow state changes that are effects of global configuration changes. Flow-path determination is triggered by any change in a flow-related device variable in a simulation or analysis. Components (path elements) that may be affected are identified, and flow-related attributes favoring flow in the two possible directions are collected for each of them. Next, flow-related attributes are determined for each affected path element, based on possibly conflicting indications of flow direction. Spurious qualitative ambiguities are minimized by using relative magnitudes and permissible directions of flow, and by favoring flow sources over effort sources when comparing flow tendencies. The results are output to local flow states of affected components.

Claims

1. A recording medium readable by a computer, tangibly embodying a program of instructions executable by the computer to perfom method steps of modeling and analysis of flow configurations, said method step comprising:

qualitatively modeling flow transmission path elements for systems of connected components and their connections to an environment,

constructing flow transmission path structures from said path elements,

aggregating said flow transmission path structures into aggregate data structures that are circuits of sub-graphs,

inputting local flow state change data into said path structures form models in simulations or analyses,

evaluating effects of local flow changes from a simulation or analysis model on the global flow transmission path configuration and the local flow states of components of the system model in order to produce flow state information, and

outputting the flow state information to local component models, and using the flow state information and the local component models in simulations and analyses.

2. The recording medium of claim 1 wherein the step of qualitatively modeling flow transmission path elements includes providing a set of qualitative flow path elements for use in the steps of constructing flow transmission path structures, aggregating said flow transmission path structures into circuits of sub-graphs, and evaluating effects of local flow changes on the global flow transmission path configuration and the local flow states of components of the system.

3. The recording medium of claim 2 wherein the step of providing a set of qualitative flow path elements includes providing resistive types, effort-source types, and flow-source types for representing components and aggregates, and junctions for representing divergences and convergences of flow.

4. The recording medium of claim 2 wherein the step of providing a set of qualitative flow path elements includes providing an abstraction of flow transmission variables, including flow and effort variables, for elements of flow paths that includes combining flow and resistance into a qualitative-potential variable, and includes qualitative information on resistance indicating substantially finite and substantially infinite resistance, net flow indicating substantially zero and flow in first and second directions, permissible directions of flow, and effort-input.

5. The recording medium of claim 1 wherein the step of qualitatively modeling flow transmission path elements includes providing flow-related variables and an internal flow map for each type of component model for simulations or analyses that inputs local flow state changes for said evaluation of global and local effects.

6. The recording medium of claim 5 wherein the step of providing flow-related variables and an internal flow map for each said type of component model includes providing "virtual" circuits that include a junction to the external model environment for storage device types.

7. The recording medium of claim 1 wherein the step of constructing flow transmission path structures includes the steps of:

manually establishing the connections between component models, and

automatically establishing the internal connections of path elements contained within the device model by reference to said flow map for that type of component model.

8. The recording method of claim 1 wherein the step of aggregating said flow transmission path structures into circuits of sub-graphs includes the steps of:

clustering the serial and parallel structures of the flow transmission path structure into sub-graphs,

including said clusters in circuit structures for sub-graphs of said path structure that cannot be clustered by strict reduction of serial and parallel paths, and

using said sub-graphs as individual nodes in a circuit.

9. The recording medium of claim 8 wherein the step of including said clusters in circuit structures uses circuits that are any collection of system components defining a cyclic path such that no path element nodes are repeated in the path sequence.

10. The recording medium of claim 8 wherein the step of using said sub-graphs as individual nodes in a circuit includes using qualitative information on resistance indicating substantially finite and substantially infinite resistance, net flow indicating substantially zero and flow in first and second directions, permissible directions of flow, and effort-input, and also directional path information and cluster-circuit interface information.

11. The recording medium of claim 1 wherein the step of inputting local flow state change data into said path structures from models in simulations or analyses includes

providing for each internal node in a component model in a simulation or analysis, a corresponding map node for the component type, to establish internal connections for said component that mirror the connections of the corresponding flow map nodes, and

providing that any change in a flow-related device variable in the simulation or analysis triggers flow-path determination.

12. The recording medium of claim 1 wherein the step of evaluating effects of local flow changes from a simulation or analysis model on the global flow transmission path configuration and the local flow states of components of the system model includes the steps of:

identifying components that may be affected,

collecting for each affected node, flow-related attributes favoring flow in the two possible directions, and

determining flow-related properties for each affected path element.

13. The recording medium of claim 12 wherein the step of evaluating effects of determining flow-related properties for each affected path element includes considering possibly conflicting flow tendencies and choosing the flow direction while resolving any ambiguities.

14. The recording medium of claim 13 wherein the step of resolving any ambiguities when comparing flow tendencies includes using information on permissible directions of flow, favoring flow sources over effort sources, distinguishing qualitative values of significant magnitude from those of relatively insignificant magnitude, or else asking the user.

15. The recording medium of claim 1 wherein the step of outputting flow state information to local component models in simulations or analyses includes linking to associated local flow states of components of the simulation or analysis that triggered the determination method.

16. A computer program product for controlling a computer to model and analyze flow configurations, the program product comprising:

a recording medium readable by the computer,

means recorded on the recording medium for qualitatively modeling flow transmission path elements for systems of connected components and their connections to an environment,

means recorded on the recording medium for constructing flow transmission path structures from said path elements,

means recorded on the recording medium for aggregating said flow transmission path structures into aggregate data structures that are circuits of sub-graphs,

means recorded on the recording medium for inputting local flow state change data into said path structures from models in simulations or analyses,

means recorded on the recording medium for evaluating effects of local flow changes from a simulation or analysis model on the global flow transmission path configuration and the local flow states of components of the system model in order to produce flow state information, and

means recorded on the recording medium for outputting flow state information from the means for evaluating to local component models, and for using the flow state information and local component models in simulations and analyses.

17. The computer program product of claim 16 wherein the means for qualitatively modeling flow transmission path elements includes means for providing a set of qualitative flow path elements for use in construction of flow transmission path structures, aggregation of said flow transmission path structures into circuits of sub-graphs, and evaluation of effects of local flow changes on the global flow transmission path configuration and the local flow states of components of the system.

18. The computer program product of claim 17 wherein the means for providing a set of qualitative flow path elements includes means for providing resistive types, effort-source types, and flow-source types for representing components and aggregates, and junctions for representing divergences and convergences of flow.

19. The computer program product of claim 17 wherein the means for providing a set of qualitative flow path elements includes means for providing an abstraction of flow transmission variables, including flow and effort variables, for elements of flow paths that includes combining flow and resistance into a qualitative-potential variable, and includes qualitative information on resistance indicating substantially finite and substantially infinite resistance, net flow indicating substantially zero and flow in first and second directions, permissible directions of flow, and effort-input.

20. The computer program product of claim 16 wherein the means for qualitatively modeling flow transmission path elements includes means for providing flow-related variables and an internal flow map for each type of component model for simulations or analyses that inputs local flow state changes for said evaluation of global and local effects.

21. The computer program product of claim 20 wherein the means for providing flow-related variables and an internal flow map for each said type of component model includes means for providing "virtual" circuits that include a junction to the external model environment for storage device types.

22. The computer program product of claim 16 wherein the means for constructing flow transmission path structures is comprised of:

means for manually establishing the connections between component models, and

means for automatically establishing the internal connections of path elements contained within the

device model by reference to said flow map for that type of component model.

23. The computer program product of claim 16 wherein the means for aggregating said flow transmission path structures into circuits of sub-graphs is comprised of:

means for clustering the serial and parallel structures of the flow transmission path structure into sub-graphs,

means for including said clusters in circuit structures for sub-graphs of said path structure that cannot be clustered by strict reduction of serial and parallel paths, and

means for using said sub-graphs as individual nodes in a circuit.

24. The computer program product of claim 23 wherein the means for including said clusters in circuit structures uses circuits that are any collection of system components defining a cyclic path such that no path element nodes are repeated in the path sequence.

25. The computer program product of claim 23 wherein the means for using said sub-graphs as individual nodes in a circuit includes means for using the same types of qualitative information as path elements, and also directional path information and cluster-circuit interface information.

26. The computer program product of claim 16 wherein the means for inputting local flow state change data into said path structures from models in simulations or analyses is comprised of:

means for providing for each internal node in a component model in a simulation or analysis, a corresponding map node for the component type, to establish internal connections for said component that mirror the connections of the corresponding flow map nodes,

and means for providing that any change in a flow-related device variable in the simulation or analysis triggers flow-path determination.

27. The computer program product of claim 16 wherein the means for evaluating effects of local flow changes from a simulation or analysis model on the global flow transmission path configuration and the local flow states of components of the system model is comprised of:

means for identifying components that may be affected,

means for collecting for each affected node, flow-related attributes favoring flow in the two possible directions,

and means for determining flow-related properties for each affected path element.

28. The computer program product of claim 27 wherein the means for evaluating effects of determining flow-related properties for each affected path element includes means for considering possibly conflicting flow tendencies and choosing the flow direction while resolving any ambiguities.

29. The computer program product of claim 28 wherein the means for resolving any ambiguities when comparing flow tendencies includes means for using information on permissible directions of flow, favoring flow sources over effort sources, distinguishing qualitative values of significant magnitude from those of relatively insignificant magnitude, or else asking the user.

30. The computer program product of claim 16 wherein the means for outputting flow state information to local component models in simulations or analyses includes means for linking to associated local flow states of components of the simulation or analysis that triggered the determination method.

31. A recording medium readable by a computer, tangibly embodying a program of instructions executable by the computer to perform method steps of modeling and analysis of flow configurations in discrete event simulation, said method steps comprising:

qualitatively modeling flow transmission path elements for systems of connected components and their connections to an environment,

constructing flow transmission path structures from said path elements,

aggregating said flow transmission path structures into aggregate data structures that are circuits of sub-graphs,

inputting local flow state change data into said path structures from models in discrete event simulations,

evaluating effects of local flow changes from a simulation or analysis model on the global flow transmission path configuration and the local flow states of components of the system model in order to produce flow state information, and

outputting the flow state information to local component models, and using the flow state information and the local component models in discrete event simulations.

32. The recording medium of claim 31 wherein the step of qualitatively modeling flow transmission path elements includes providing a set of qualitative flow path elements for use in the steps of constructing flow transmission path structures, aggregating said flow transmission path structures into circuits of sub-graphs, and evaluating effects of local flow changes on the global flow transmission path configuration and the local flow states of components of the system.

33. The recording medium of claim 32 wherein the step of providing a set of qualitative flow path elements includes providing resistive types, effort-source types, and flow-source types for representing components and aggregates, and junctions for representing divergences and convergences of flow.

34. The recording medium of claim 32 wherein the step of providing a set of qualitative flow path elements includes providing an abstraction of flow transmission variables, including flow and effort variables, for elements of flow paths that includes combining flow and resistance into a qualitative-potential variable, and includes qualitative information on resistance indicating substantially finite and substantially infinite resistance, net flow indicating substantially zero and flow in first and second directions, permissible directions of flow, and effort-input.

35. The recording medium of claim 31 wherein the step of qualitatively modeling flow transmission path elements includes providing flow-related variables and an internal flow map for each type of component model for discrete event simulations that inputs local flow state changes for said evaluation of global and local effects.

36. The recording medium of claim 35 wherein the step of providing flow-related variables and an internal flow map for each said type of component model includes providing "virtual" circuits that include a junction to the external model environment for storage device types.

37. The recording medium of claim 31 wherein the step of constructing flow transmission path structures includes the steps of:

manually establishing the connections between component models,

and automatically establishing the internal connections of path elements contained within the component model by reference to said flow map for that type of component model.

38. The recording medium of claim 31 wherein the step of aggregating said flow transmission path structures into circuits of sub-graphs includes the steps of:

clustering the serial and parallel structures of the flow transmission path structure into sub-graphs,

including said clusters in circuit structures for sub-graphs of said path structure that cannot be clustered by strict reduction of serial and parallel paths, and

using said sub-graphs as individual nodes in a circuit.

39. The recording medium of claim 38 wherein the step of including said clusters in circuit structures uses circuits that are any collection of system components defining a cyclic path such that no path element nodes are repeated in the path sequence.

40. The recording medium of claim 38 wherein the step of using said sub-graphs as individual nodes in a circuit includes using qualitative information on resistance indicating substantially finite and substantially infinite resistance, net flow indicating substantially zero and flow in first and second directions, permissible directions of flow, and effort-input, and also directional path information and cluster-circuit interface information.

41. The recording medium of claim 31 wherein the step of inputting local flow state change data into said path structures from models in discrete event simulations includes

providing for each internal node in a component model in a discrete event simulation, a corresponding map node for the component type, to establish internal connections for said component that mirror the connections of the corresponding flow map nodes, and

providing that any change in a flow-related device variable in the discrete event simulation triggers flow-path determination.

42. The recording medium of claim 31 wherein the step of evaluating effects of local flow changes from a discrete event simulation model on the global flow transmission path configuration and the local flow states of components of the system model includes the steps of:

identifying components that may be affected,

collecting for each affected node, flow-related attributes favoring flow in the two possible directions, and

determining flow-related properties for each affected path element.

43. The recording medium of claim 40 wherein the step of evaluating effects of determining flow-related properties for each affected path element includes considering possibly conflicting flow tendencies and choosing the flow direction while resolving any ambiguities.

44. The recording medium of claim 43 wherein the step of resolving any ambiguities when comparing flow tendencies includes using information on permissible directions of flow, favoring flow sources over effort sources, distinguishing qualitative values of significant magnitude from those of relatively insignificant magnitude, or else asking the user.

45. The recording medium of claim 31 wherein the step of outputting flow state information to local component models in discrete event simulations includes linking to associated local flow states of components of the simulation that triggered the determination method.

46. A computer program product for controlling a computer to model and analyze flow configurations in discrete event simulation, the program product comprising:

a recording medium readable by the computer,

means recorded on the recording medium for qualitatively modeling flow transmission path elements for systems of connected components and their connections to an environment,

means recorded on the recording medium for constructing flow transmission path structures from said path elements,

means recorded on the recording medium for aggregating said flow transmission path structures into aggregate data structures that are circuits of sub-graphs,

means recorded on the recording medium for inputting local flow state change data into said path structures from models in discrete event simulations,

means recorded on the recording medium for evaluating effects of local flow changes from a discrete event simulation model on the global flow transmission path configuration and the local flow states of components of the system model in order to produce flow state information, and

means recorded on the recording medium for outputting the flow state information to local component models, and for using the flow state information and the local component models in discrete event simulations.

47. The computer program product of claim 46 wherein the means for qualitatively modeling flow transmission path elements includes means for providing a set of qualitative flow path elements for use in construction of flow transmission path structures, aggregation of said flow transmission path structures into circuits of sub-graphs, and evaluation of effects of local flow changes on the global flow transmission path configuration and the local flow states of components of the system.

48. The computer program product of claim 47 wherein the means for providing a set of qualitative flow path elements includes means for providing resistive types, effort-source types, and flow-source types for representing components and aggregates, and junctions for representing divergences and convergences of flow.

49. The computer program product of claim 47 wherein the means for providing a set of qualitative flow path elements includes means for providing an abstraction of flow transmission variables, including flow and effort variables, for elements of flow paths that includes combining flow and resistance into a qualitative-potential variable, and includes qualitative information on resistance indicating substantially finite and substantially infinite resistance, net flow indicating substantially zero and flow in first and second directions, permissible directions of flow, and effort-input.

50. The computer program product of claim 46 wherein the means for qualitatively modeling flow transmission path elements includes means for providing flow-related variables and an internal flow map for each type of component model for discrete event simulations that input local flow state changes for said evaluation of global and local effects.

51. The computer program product of claim 50 wherein the means for providing flow-related variables and an internal flow map for each said type of component model includes means for providing "virtual" circuits that include a junction to the external model environment for storage device types.

52. The computer program product of claim 46 wherein the means for constructing flow transmission path structures is comprised of:

means for manually establishing the connections between component models, and

means for automatically establishing the internal connections of path elements contained within the component model by reference to said flow map for that type of component model.

53. The computer program product of claim 46 wherein the means for aggregating said flow transmission path structures into circuits of sub-graphs is comprised of:

means for clustering the serial and parallel structures of the flow transmission path structure into sub-graphs,

means for including said clusters in circuit structures for sub-graphs of said path structure that cannot be clustered by strict reduction of serial and parallel paths, and

means for using said sub-graphs as individual nodes in a circuit.

54. The computer program product of claim 53 wherein the means for including said clusters in circuit structures uses circuits that are any collection of system components defining a cyclic path such that no path element nodes are repeated in the path sequence.

55. The computer program product of claim 53 wherein the means for using said sub-graphs as individual nodes in a circuit includes means for using the same types of qualitative information as path elements, and also directional path information and cluster-circuit interface information.

56. The computer program product of claim 46 wherein the means for inputting local flow state change data into said path structures from models in discrete event simulations is comprised of:

means for providing for each internal node in a component model in a discrete event simulation, a

corresponding map node for the component type, to establish internal connections for said component that mirror the connections of the corresponding flow map nodes, and

means for providing that any change in a flow-related device variable in said discrete event simulation triggers flow-path determination.

57. The computer program product of claim 46 wherein the means for evaluating effects of local flow changes from a discrete event simulation model on the global flow transmission path configuration and the local flow states of components of the system model is comprised of:

means for identifying components that may be affected,

means for collecting for each affected node, flow-related attributes favoring flow in the two possible

directions, and

means for determining flow-related properties for each affected path element.

58. The computer program product of claim 57 wherein the means for evaluating effects of determining flow-related properties for each affected path element includes means for considering possibly conflicting flow tendencies and choosing the flow direction while resolving any ambiguities.

59. The computer program product of claim 58 wherein the means for resolving any ambiguities when comparing flow tendencies includes means for using information on permissible directions of flow, favoring flow sources over effort sources, distinguishing qualitative values of significant magnitude from those of relatively insignificant magnitude, or else asking the user.

60. The computer program product of claim 46 wherein the means for outputting flow state information to local component models in discrete event simulations includes means for linking to associated local flow states of components of the simulation or analysis that triggered the determination method.

61. A recording medium readable by a computer, tangibly embodying a program of instructions executable by the computer to perform method steps of modeling and analysis of flow configurations in a discrete event simulation, said method steps comprising:

qualitatively modeling flow transmission path elements for systems of connected components and their connections to an environment,

constructing flow transmission path structures from said path elements,

aggregating said flow transmission path structures into aggregate data structures that are circuits of sub-graphs,

inputting local flow state change data into said path structures from models in discrete event simulations,

evaluating effects of local flow changes from a simulation model on the global flow transmission path configuration and the local flow states of components of the system model in order to produce flow state information, and

outputting the flow state information to local component models, and using the flow state information and the local component models in the discrete event simulation,

wherein the step of evaluating effects of local flow changes from a discrete event simulation model on the global flow transmission path configuration and the local flow states of components of the system model includes the steps of;

identifying components that my be affected,

collecting for each affected node, flow-related attributes favoring flow in the two possible directions, and

determining flow-related properties for each affected path component, and

wherein the step of collecting for each affected node, flow-related attributes favoring flow in the two possible directions, is completed for all of the components identified by the step of identifying components that may be affected, prior to the step of determining flow-related properties for each affected path element, in order to delay the step of determining flow-related properties for each affected path element until the end of a discrete-event time quantum for said discrete event simulations.

62. The recording medium of claim 61, wherein the step of determining flow-related properties for each affected path element includes considering possibly conflicting flow tendencies and choosing the flow direction while resolving any ambiguities by using information on permissible directions of flow, favoring flow sources over effort sources, distinguishing qualitative values of significant magnitude from those of relatively insignificant magnitude, or else asking the user.

63. The recording medium of claim 61,

wherein the step of qualitatively modeling flow transmission path elements includes providing a set of qualitative flow path elements for use in the steps of constructing flow transmission path structures, aggregating said flow transmission path structures into circuits of sub-graphs, and evaluating effects of local flow changes on the global flow transmission path configuration and the local flow states of components of the system, and

wherein the step of providing a set of qualitative flow path elements includes providing an abstraction of flow transmission variables, including flow and effort variables, for elements of flow paths that includes combining flow and resistance into a qualitative-potential variable, and includes qualitative information on resistance indicating substantially finite and substantially infinite resistance, net flow indicating substantially zero and flow in first and second directions, permissible directions of flow, and effort-input.

64. The recording medium of claim 61,

wherein the step of qualitatively modeling flow transmission path elements includes providing flow-related variables and an internal flow map for each type of component model for simulations or analyses that inputs local flow state changes for said evaluation of global and local effects, and

wherein the providing of flow-related variables and an internal flow map for each said type of component model includes providing "virtual" circuits that include a junction to the external model environment for storage device types.

65. The recording medium of claim 61 wherein the step of aggregating said flow transmission path structures into circuits of sub-graphs includes the steps of:

clustering the serial and parallel structures of the flow transmission path structure into sub-graphs,

including said clusters in circuit structures for sub-graphs of said path structure that cannot be clustered by strict reduction of serial and parallel paths, and

using said sub-graphs as individual nodes in a circuit.

66. The recording medium of claim 65 wherein the step of including said clusters in circuit structures uses circuits that are any collection of system components defining a cyclic path such that no path element nodes are repeated in the path sequence.

67. A recording medium readable by a computer, tangibly embodying a program of instructions executable by the computer to perform method steps of modeling and analysis of flow configurations in discrete event simulation, said program of instructions comprising:

a program executable by the computer for building models in the computer of physical components and a model of a physical system comprised of selected ones of the physical components;

a program executable by the computer for performing a discrete event simulation of said physical system using said models of the physical system and the selected ones of the physical components in the physical system; and

a flow path management program executable by the computer for;

qualitatively modeling flow transmission path elements for the physical system and connections to and environment of the physical system,

constructing flow transmission path structures from said path elements,

aggregating said flow transmission path structures into aggregate data structures that are circuits of sub-graphs,

inputting local flow state change data into said path structures from said models during a discrete event simulation by execution of said simulation program,

evaluating effects of local flow changes from said models on the global flow transmission path configuration and the local flow states of components of the system model in order to produce flow state information, and

outputting the flow state information to local component models,

wherein the simulation program is executable by the computer for using the flow state information and the local component models in the discrete event simulation,

wherein the flow management program is executable by the computer for evaluating effects of local flow changes from a discrete event simulation model on the global flow transmission path configuration and the local flow states of components of the system model by;

identifying components that may be affected,

collecting for each affected node, flow-related attributes favoring flow in the two possible directions, and

determining flow-related properties for each affected path element, and

wherein the collecting for each affected node, flow-related attributes favoring flow in the two possible directions, is completed for all of the components identified by the stop of identifying components that may be affected, prior to the determining of flow-related properties for each affected path element, in order to delay the determining of flow-related properties for each affected path element until the end of a discrete-event time quantum for said discrete event simulation.

68. The recording medium of claim 67, wherein the flow path management program is executable by the computer for evaluating effects of determining flow-related properties for each affected path element by considering possibly conflicting flow tendencies and choosing the flow direction while resolving any ambiguities, and resolving any ambiguities when comparing flow tendencies by using information on permissible directions of flow, favoring flow sources over effort sources, distinguishing qualitative values of significant magnitude from those of relatively insignificant magnitude, or else asking the user.

69. The recording medium as recited in claim 67, wherein the flow path management program is executable by the computer for qualitatively modeling flow transmission path elements by constructing flow transmission path structures, aggregating said flow transmission path structures into circuits of sub-graphs, and evaluating effects of local flow changes on the global flow transmission path configuration and the local flow states of components of the system, and

wherein the qualitative modeling of flow transmission path elements includes using an abstraction of flow transmission variables, including flow and effort variables, for elements of flow paths that includes combining flow and resistance into a qualitative-potential variable, and includes qualitative information on resistance indicating substantially finite and substantially infinite resistance, net flow indicating substantially zero and flow in first and second directions, permissible directions of flow, and effort-input.

70. The recording medium of claim 67,

wherein the flow path management program is executable by the computer for accessing models of flow transmission path elements including flow-related variables and an internal flow map for each type of component model for discrete event simulation that inputs local flow state changes for said evaluation of global and local effects, and

wherein the flow-related variables and an internal flow map for each said type of component model includes flow-related variables and an internal flow map for "virtual" circuits that include a junction to the external model environment for storage device types.

71. The recording medium of claim 69 wherein the flow path management program is executable by the computer for aggregating said flow transmission path structures into circuits of sub-graphs by:

clustering the serial and parallel structures of the flow transmission path structure into sub-graphs,

including said clusters in circuit structures for sub-graphs of said path structure that cannot be clustered by strict reduction of serial and parallel paths, and

using said sub-graphs as individual nodes in a circuit.

72. The recording medium of claim 71 wherein the clusters in circuit structures use circuits that are any collection of system components defining a cyclic path such that no path element nodes are repeated in the path sequence.