1. A method of simulating parametric variations in an integrated circuit (IC) comprising:
specifying an IC model, wherein the IC model includes one or more parameters for variation about a nominal condition;
calculating parametric perturbations about the nominal condition, wherein calculating the parametric perturbations includes:
simulating the nominal condition for the IC;
determining perturbation values for the IC model about the nominal conditions, wherein the perturbation values include linear time-varying matrices and parametric right-hand sides,
determining a performance metric for the IC and a performance sampling vector for sampling the performance metric about the nominal condition from the perturbation values; and
determining voltage-sensitivity values and performance-sensitivity values from the perturbation values and the performance-sampling vector; and
saving one or more values for the parametric perturbations in a computer-readable medium.
2. A method according to claim 1, wherein the performance metric measures delay for a waveform and the performance sampling vector samples waveform values to measure the delay.
3. A method according to claim 1, wherein simulating the nominal condition for the IC includes approximating IC behavior on a discrete temporal grid.
4. A method according to claim 1, wherein the linear time-varying matrices include capacitance values and conductance values.
5. A method according to claim 1, wherein the parametric right-hand sides include source functions corresponding to parametric variations.
6. A method according to claim 1, wherein the performance-sampling vector corresponds to a reference voltage value that crosses a threshold voltage value.
7. A method according to claim 1, wherein determining the voltage sensitivity values and performance sensitivity values includes solving a system that relates values of the linear time-varying matrices to the parametric right-hand sides.
8. A method according to claim 1, wherein calculating the parametric perturbations further comprises: determining a performance value from the performance sensitivity.
9. A method according to claim 1, wherein
the perturbation values for the IC model include a first-order system that is driven by source functions that correspond to the parametric perturbations and a second-order system that is driven by a solution of the first-order system; and
determining the voltage-sensitivity values includes solving the first-order system for a first-order voltage sensitivity and using the first-order voltage sensitivity to solve the second-order system for a second-order voltage sensitivity.
10. A method according to claim 1, wherein
the perturbation values for the IC model include a first-order system that is driven by source functions that correspond to the parametric perturbations and a second-order system that is driven by a solution of the first-order system; and
determining the performance-sensitivity values includes solving the first-order system for a first-order voltage sensitivity, solving an adjoint first-order system for a performance-sampling sensitivity corresponding to the performance-sampling vector, and calculating a second-order performance sensitivity by using the second-order system to combine the first-order voltage sensitivity and the performance-sampling sensitivity.
11. An apparatus for simulating parametric variations in an integrated circuit (IC), the apparatus comprising a computer for executing computer instructions, wherein the computer includes computer instructions for:
specifying an IC model, wherein the IC model includes one or more parameters for variation about a nominal condition;
calculating parametric perturbations about the nominal condition, wherein calculating the parametric perturbations includes:
simulating the nominal condition for the IC;
determining perturbation values for the IC model about the nominal conditions, wherein the perturbation values include linear time-varying matrices and parametric right-hand sides,
determining a performance metric for the IC and a performance sampling vector for sampling the performance metric about the nominal condition from the perturbation values; and
determining voltage-sensitivity values and performance-sensitivity values from the perturbation values and the performance-sampling vector; and
saving one or more values for the parametric perturbations.
12. An apparatus according to claim 11, wherein the computer includes a processor with memory for executing at least some of the computer instructions.
13. An apparatus according to claim 11, wherein the computer includes circuitry for executing at least some of the computer instructions.
14. An apparatus according to claim 11, wherein the performance metric measures delay for a waveform and the performance sampling vector samples waveform values to measure the delay.
15. An apparatus according to claim 11, wherein
the perturbation values for the IC model include a first-order system that is driven by source functions that correspond to the parametric perturbations and a second-order system that is driven by a solution of the first-order system; and
determining the voltage-sensitivity values includes solving the first-order system for a first-order voltage sensitivity and using the first-order voltage sensitivity to solve the second-order system for a second-order voltage sensitivity.
16. An apparatus according to claim 11, wherein
the perturbation values for the IC model include a first-order system that is driven by source functions that correspond to the parametric perturbations and a second-order system that is driven by a solution of the first-order system; and
determining the performance-sensitivity values includes solving the first-order system for a first-order voltage sensitivity, solving an adjoint first-order system for a performance-sampling sensitivity corresponding to the performance-sampling vector, and calculating a second-order performance sensitivity by using the second-order system to combine the first-order voltage sensitivity and the performance-sampling sensitivity.
17. A computer-readable medium that stores a computer program for simulating parametric variations in an integrated circuit (IC), wherein the computer program includes instructions for:
specifying an IC model, wherein the IC model includes one or more parameters for variation about a nominal condition;
calculating parametric perturbations about the nominal condition, wherein calculating the parametric perturbations includes:
simulating the nominal condition for the IC;
determining perturbation values for the IC model about the nominal conditions, wherein the perturbation values include linear time-varying matrices and parametric right-hand sides,
determining a performance metric for the IC and a performance sampling vector for sampling the performance metric about the nominal condition from the perturbation values; and
determining voltage-sensitivity values and performance-sensitivity values from the perturbation values and the performance-sampling vector; and
saving one or more values for the parametric perturbations.
18. A computer-readable medium according to claim 17, wherein the performance metric measures delay for a waveform and the performance sampling vector samples waveform values to measure the delay.
19. A computer-readable medium according to claim 17, wherein
the perturbation values for the IC model include a first-order system that is driven by source functions that correspond to the parametric perturbations and a second-order system that is driven by a solution of the first-order system; and
determining the voltage-sensitivity values includes solving the first-order system for a first-order voltage sensitivity and using the first-order voltage sensitivity to solve the second-order system for a second-order voltage sensitivity.
20. A computer-readable medium according to claim 17, wherein
the perturbation values for the IC model include a first-order system that is driven by source functions that correspond to the parametric perturbations and a second-order system that is driven by a solution of the first-order system; and
determining the performance-sensitivity values includes solving the first-order system for a first-order voltage sensitivity, solving an adjoint first-order system for a performance-sampling sensitivity corresponding to the performance-sampling vector, and calculating a second-order performance sensitivity by using the second-order system to combine the first-order voltage sensitivity and the performance-sampling sensitivity.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. Apparatus for adjustably transitioning a flow of crop residue expelled from an axially arranged threshing system of an agricultural combine so as to flow into a crop residue distribution system of the combine, comprising:
a deflector at a pivotally mounted adjacent to the threshing system so as to be to in a path of the flow of crop residue when expelled from the threshing system thereof such that at least a portion of the flow will impinge the deflector and be deflected thereby downwardly into the crop residue distribution system, the deflector rotatable about a pivotal axis, the pivotal axis being substantially parallel to a longitudinal axis of the threshing system; and
an adjusting mechanism operable for moving the deflector within the path of the flow of the crop residue for changing a transverse location of the deflector at which the flow deflected by the deflector will flow into the crop residue distribution system.
2. The apparatus of claim 1, wherein the adjusting mechanism is operable for moving the deflector in the first transverse direction for moving the transverse location at which the flow deflected by the deflector will flow into the crop residue distribution system in a first transverse direction, and the adjusting mechanism is operable for moving the deflector in a second transverse direction for moving the transverse location at which the flow deflected by the deflector will flow into the crop residue distribution system in the second transverse direction.
3. The apparatus of claim 2, wherein the deflector includes an upper portion and a lower portion, the upper portion being pivotally mounted in the combine such that at least the lower portion is located in the path of the flow.
4. The apparatus of claim 3, wherein the lower portion of the deflector includes a tapered lower edge.
5. The apparatus of claim 2, wherein the deflector is pivotable transversely between a generally upstanding orientation and a range of orientations at acute angles to the upstanding orientation.
6. The apparatus of claim 1, wherein the adjusting mechanism comprises a remotely controllable actuator.
7. The apparatus of claim 1, wherein the threshing system includes a rotor rotatable within a concave for expelling the flow of crop residue through a discharge opening into a passage extending downwardly into the crop residue distribution system, and the deflector is positioned in the path of the flow adjacent to a side of the passage.
8. The apparatus of claim 7, wherein the deflector has an upper portion pivotally mounted in a space between the concave and a side structure of the combine for transverse pivotal movement of a lower portion of the deflector in the path of the flow of crop residue.
9. The apparatus of claim 1, wherein the deflector has a curved shape.
10. The apparatus of claim 1, wherein the adjusting mechanism operable for moving the deflector within the path of the flow of the crop residue for approximately centering the flow of crop residue into the crop residue distribution system about an axial center line thereof.
11. Apparatus for adjustably transitioning a flow of crop residue from a discharge opening of an axially arranged threshing system of a combine so as to flow downwardly into a selectable region of a crop residue distribution system of the combine comprising:
a deflector pivotally mounted adjacent to an internal side of the combine generally along which the flow is directed such that at least a portion of the flow will strike the deflector and be deflected thereby downwardly into the crop residue distribution system, the deflector rotatable about a pivotal axis, the pivotal axis being substantially parallel to a longitudinal axis of the combine; and
an adjusting mechanism operable for moiling the deflector in relation to the internal side for adjusting a transverse location at which the flow will enter the crop residue distribution system.
12. The apparatus of claim 11, wherein the adjusting mechanism is operable for moving the deflector for approximately centering the flow about an axial center of the crop residue system.
13. The apparatus of claim 11, wherein the deflector includes a lower edge having a tapered shape.
14. The apparatus of claim 11, wherein the deflector is pivotable transversely between a generally upstanding orientation and a range of orientations at acute angles to the upstanding orientation.
15. The apparatus of claim 11, wherein the adjusting mechanism comprises a remotely controllable actuator.
16. The apparatus of claim 11, wherein the deflector has an upper portion pivotally mounted adjacent to the internal side of the combine for transverse pivotal movement of a lower portion of the deflector relative to the internal side.
17. The apparatus of claim 11, wherein the deflector has a curved shape.
18. An agricultural combine, comprising:
an axially arranged threshing system including a rotor rotatable within a concave for discharging a flow of crop residue through a rearwardly located downwardly facing discharge opening for downward flow along an internal side defining a passage extending downwardly and rearwardly to a crop residue distribution system of the combine;
a deflector pivotally mounted adjacent to the internal side in a position such that at least a portion of the flow will strike the deflector and be deflected thereby downwardly and transversely through the passage toward the crop residue distribution system, the deflector rotatable about a pivotal axis, the pivotal axis being substantially parallel to a longitudinal axis of the rotor; and
an adjusting mechanism operable for moving the deflector in relation to the internal side for adjusting a transverse location at which the flow will enter the crop residue distribution system.
19. The apparatus of claim 18, wherein the adjusting mechanism is operable for moving the deflector for approximately centering the downwardly deflected flow about an axial center of the crop residue distribution system.
20. The apparatus of claim 18, wherein the deflector includes a tapered lower edge positioned to extend across the flow.
21. The apparatus of claim 18, wherein the deflector is pivotable transversely between a generally upstanding orientation and a range of orientations at acute angles to the upstanding orientation.
22. The apparatus of claim 18, wherein the adjusting mechanism comprises a remotely controllable actuator.