1.-4. (canceled)
5. A fuel cell system that includes a load, a fuel cell stack connected to the load and a buffer tank storing an anode gas discharged from the fuel cell stack and that is configured to supply an anode gas and a cathode gas to the fuel cell stack to generate power according to the load, the fuel cell system comprising:
a pressure setting unit configured to set a pressure of the anode gas higher when the load is high as compared with when the load is low;
a stagnation point determination unit configured to determine, at a time of a lowering transient operation where the pressure of the anode gas in a reaction flow path within the fuel cell stack is lowered by a power generation reaction of the fuel cell stack, whether or not a nitrogen stagnation point is left in a reaction flow path within the fuel cell stack; and
an operation control unit configured to perform an operation while preventing the pressure of the anode gas from being lowered when a required load is lowered in a state where the nitrogen stagnation point is left.
6. The fuel cell system of claim 5,
wherein the operation control unit is configured to allow the pressure of the anode gas to be lowered when the nitrogen stagnation point is not left after the pressure of the anode gas is prevented from being lowered.
7. The fuel cell system of claim 5,
wherein the stagnation point determination unit is configured to determine, by whether or not a time necessary to discharge the nitrogen stagnation point has elapsed, whether or not the nitrogen stagnation point is left.
8. The fuel cell system of claim 5, further comprising:
a concentration estimation unit configured to estimate, when the required load is lowered in the state where the nitrogen stagnation point is left, a hydrogen concentration after the pressure is lowered,
wherein the operation control unit is configured to, when the estimated hydrogen concentration is higher than a reference value, perform the operation without preventing the pressure of the anode gas from being lowered even if the required load is lowered in the state where the nitrogen stagnation point is left.
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. A medical device comprising:
at least one layer of a fabric of braided strands, having proximal and distal ends and a central axis extending therebetween, the medical device having an expanded preset configuration comprising a generally frustoconical shaped portion at each end, wherein, in the expanded preset configuration, each frustoconical shaped portion comprises first and second ends and a conical portion disposed therebetween, wherein the first ends are generally planar and face one another and have a larger cross-sectional diameter than the second ends, wherein the second ends correspond to the proximal and distal ends of the medical device, wherein at least one of the generally frustoconical shaped portions comprises a cylindrical portion extending from adjacent to the planar first end and connecting to the conical portion, wherein the medical device is configured to be constrained to a reduced configuration for delivery through a diagnostic catheter, and wherein the medical device is biased towards the expanded preset configuration such that the medical device is configured to self expand and at least partially return, when unconstrained, towards the expanded preset configuration.
2. The medical device of claim 1, wherein the at least one layer of fabric includes braided first and second strands with respective different first and second diameters.
3. The medical device of claim 1, wherein the ends of the braided strands are secured from unraveling on at least one of the proximal or distal ends of the device.
4. The medical device of claim 1, further comprising a pair of end clamps securing respective ends of the braided strands and configured for delivery through the diagnostic catheter.
5. The medical device of claim 4, wherein one of the end clamps includes a threaded portion.
6. The medical device of claim 1, wherein the fabric comprises a shape memory material.
7. The medical device of claim 6, wherein the shape memory material is a nickel titanium alloy.
8. The medical device of claim 1, wherein the medical device further comprises a central portion coupling the first ends of the generally frustoconical shaped portions.
9. The medical device of claim 8, wherein the medical device further comprises a central portion coupling the first ends of the generally frustoconical shaped portions.
10. The medical device of claim 9, wherein the central portion has a cross-sectional dimension substantially less than that of the first ends of the generally frustoconical shaped portions.
11. The medical device of claim 1, wherein the medical device is configured to be constrained for delivery through a diagnostic catheter having an outer diameter of 5 French or less.
12. The medical device of claim 1, wherein the medical device is configured to be constrained for delivery through a diagnostic catheter having an outer diameter of 4 French or less.
13. The medical device of claim 1, wherein the medical device is configured to be constrained to a reduced configuration having an outer diameter of less than about 0.040 inches.
14. A method of treating a target site within the body, the method comprising:
providing a medical device according to claim 1;
constraining the medical device from an expanded configuration to a reduced configuration for delivery through a diagnostic catheter;
delivering the medical device proximate to the target site; and
deploying the medical device from the diagnostic catheter such that the medical device at least partially returns towards the expanded preset configuration.
15. The method of claim 14, wherein the constraining the medical device to the reduced configuration includes axially elongating the medical device.
16. The method of claim 14, further comprising attaching one end of the medical device to a delivery device and advancing the medical device into the diagnostic catheter while attached to the delivery device.
17. The method of claim 14, wherein deploying comprises advancing the medical device through a diagnostic catheter having an outer diameter of 5 French or less.
18. The method of claim 14, wherein deploying comprises advancing the medical device through a diagnostic catheter having an outer diameter of 4 French or less.
19. The method of claim 14, further comprising injecting a contrast medium through the diagnostic catheter before delivering the medical device or after deploying the medical device from the diagnostic catheter.
20. The medical device of claim 1, wherein each frustoconical shaped portion has approximately the same maximum outer diameter.
21. The medical device of claim 1, wherein the frustoconical portions are spaced axially apart from one another along the central axis so as to define a gap therebetween.
22. The medical device of claim 21, further comprising a central portion coupling the first ends and extending within the gap.
23. The medical device of claim 1, wherein each conical portion is spaced axially from the first end towards the second end along the central axis.
24. A medical device comprising:
at least one layer of a fabric of braided strands, having proximal and distal ends and a central axis extending therebetween, the medical device having an expanded preset configuration comprising a generally frustoconical shaped portion at each end and a central portion coupling the frustoconical portions together such that the frustoconical portions are spaced axially apart from one another along the central axis, wherein, in the expanded preset configuration, each frustoconical shaped portion comprises first and second ends, wherein the first ends are generally planar and face one another and have a larger cross-sectional diameter than the second ends, wherein the second ends correspond to the proximal and distal ends of the medical device, wherein at least one of the generally frustoconical shaped portions comprises a cylindrical portion extending from adjacent to the planar first end and connecting to a conical portion, wherein the medical device is configured to be constrained to a reduced configuration for delivery through a diagnostic catheter, and wherein the medical device is biased towards the expanded preset configuration such that the medical device is configured to self expand and at least partially return, when unconstrained, towards the expanded preset configuration.
25. The medical device of claim 1, wherein the at least one layer of fabric comprises a tubular member.
26. The medical device of claim 1, wherein the at least one layer of fabric is configured to at least partially inhibit the flow of blood between the proximal and distal ends so as occlude a target site in which the medical device is delivered.
27. The medical device of claim 1, wherein the conical portion and the cylindrical portion are integrally formed from the same layer of fabric so as to be contiguous with one another.