1. An open MRI system, comprising:
an open MRI magnet system; and
a vibration isolation system supporting the MRI magnet system;
wherein:
the vibration isolation system is secured to a floor and the MRI magnet system is attached over the vibration isolation system; and
the vibration isolation system is configured within a footprint of magnets of the MRI magnet system.
2. The open MRI system of claim 1, wherein:
a spring constant and damping of the vibration isolation system are adjustable;
the vibration isolation system is site tunable; and
the vibration isolation system is tuned to minimize the magnet system Q factor and to control a bandwidth of the MRI magnet system vibration response at a predominant MRI magnet exciting frequencies.
3. The open MRI system of claim 1, wherein the vibration isolation system comprises a plurality of pneumatic isolators.
4. The open MRI system of claim 1, wherein the vibration isolation system comprises a plurality of active vibration control isolators.
5. The open MRI system of claim 1, wherein the vibration isolation system comprises:
a plurality of posts secured to the floor; and
a plurality of vibration isolators mounted on the plurality of posts and supporting the MRI magnet system.
6. The open MRI system of claim 5, further comprising an adjustable balance mass located below the MRI magnet system and between the plurality of posts.
7. The open MRI system of claim 1, further comprising a structural holder positioned between the vibration isolation system and the MRI magnet system.
8. The open MRI system of claim 1, wherein the vibration isolation system is retrofitted to a preexisting MRI magnet system.
9. The open MRI system of claim 1, wherein the open magnet system comprises:
(a) a first assembly comprising:
(1) a longitudinally-extending and generally-vertically-aligned first axis;
(2) at least one superconductive main coil positioned around said first axis and carrying a first main electric current in a first direction; and
(3) a first vacuum enclosure enclosing said at least one superconductive main coil of said first assembly;
(b) a second assembly longitudinally spaced apart from and disposed below said first assembly, comprising:
(1) a longitudinally-extending second axis generally coaxially aligned with said first axis;
(2) at least one superconductive main coil positioned around said second axis and carrying a second main electric current in said first direction; and
(3) a second vacuum enclosure enclosing said at least one superconductive main coil of second assembly; and
(c) at least one support beam external to said first and second vacuum enclosures having a first end attached to said first assembly and having a second end attached to said second assembly.
10. An open MRI system, comprising:
an open MRI magnet system;
a vibration isolation system supporting the MRI magnet system; and
a balance mass located below the MRI magnet system.
11. The open MRI system of claim 10, wherein:
a spring constant and damping of the vibration isolation system are adjustable;
the vibration isolation system is site tunable; and
the vibration isolation system is tuned to minimize the magnet system Q factor and to control a bandwidth of the MRI magnet system vibration response at a predominant MRI magnet exciting frequencies.
12. The open MRI system of claim 10, wherein the vibration isolation system comprises a plurality of pneumatic isolators.
13. The open MRI system of claim 10, wherein the vibration isolation system comprises a plurality of active vibration control isolators.
14. The open MRI system of claim 10, wherein the balance mass is adjustable.
15. The open MRI system of claim 10, wherein:
the vibration isolation system is secured to a floor and the MRI magnet system is attached over the vibration isolation system; and
the vibration isolation system is configured within a footprint of the MRI magnet system.
16. The open MRI system of claim 15, wherein the vibration isolation system comprises:
a plurality of posts secured to the floor, such that the balance mass is located between the plurality of posts; and
a plurality of vibration isolators mounted on the plurality of posts and supporting the MRI magnet system.
17. The open MRI system of claim 10, wherein the vibration isolation system is retrofitted to a preexisting MRI magnet system.
18. The open MRI system of claim 10, wherein the open MRI magnet system comprises:
(a) a first assembly comprising:
(1) a longitudinally-extending and generally-vertically-aligned first axis;
(2) at least one superconductive main coil positioned around said first axis and carrying a first main electric current in a first direction; and
(3) a first vacuum enclosure enclosing said at least one superconductive main coil of said first assembly;
(b) a second assembly longitudinally spaced apart from and disposed below said first assembly, comprising:
(1) a longitudinally-extending second axis generally coaxially aligned with said first axis;
(2) at least one superconductive main coil positioned around said second axis and carrying a second main electric current in said first direction; and
(3) a second vacuum enclosure enclosing said at least one superconductive main coil of second assembly; and
(c) at least one support beam external to said first and second vacuum enclosures having a first end attached to said first assembly and having a second end attached to said second assembly.
19. An open MRI system, comprising:
an open MRI magnet system;
a vibration isolation system supporting the MRI magnet system; and
a balance mass located below the MRI magnet system;
wherein:
the vibration isolation system is secured to a floor and the MRI magnet system is attached over the vibration isolation system; and
the vibration isolation system is configured within a footprint of the MRI magnet system.
20. The open MRI system of claim 19, wherein:
the balance mass is adjustable; and
the vibration isolation system comprises:
a plurality of posts secured to the floor, such that the balance mass is located between the plurality of posts; and
a plurality of vibration isolators mounted on the plurality of posts and supporting the MRI magnet system.
21. An open MRI system, comprising:
an open superconductive MRI magnet system; and
a vibration isolation system supporting the MRI magnet system;
wherein:
a spring constant and damping of the vibration isolation system are adjustable;
the vibration isolation system is site tunable; and
the vibration isolation system is tuned to minimize the magnet system Q factor and to control a bandwidth of the MRI magnet system vibration response at a predominant MRI magnet exciting frequencies.
22. An open MRI system, comprising:
an open superconductive MRI magnet system; and
a vibration isolation system supporting the MRI magnet system;
wherein the vibration isolation system comprises a plurality of active vibration control isolators.
23. The open MRI system of claim 21, further comprising:
a structural holder positioned between the vibration isolation system and the MRI magnet system.
24. The open MRI system of claim 23, wherein the vibration isolation system comprises a plurality of pneumatic isolators.
25. The open MRI system of claim 23, wherein the vibration isolation system comprises:
a plurality of posts secured to the floor; and
a plurality of vibration isolators mounted on the plurality of posts and supporting the MRI magnet system.
26. The open MRI system of claim 25, further comprising an adjustable balance mass located below the MRI magnet system and between the plurality of posts.
27. The open MRI system of claim 23, wherein the vibration isolation system is retrofitted to a preexisting MRI magnet system.
28. The open MRI system of claim 23, wherein the open magnet system comprises:
(a) a first assembly comprising:
(1) a longitudinally-extending and generally-vertically-aligned first axis;
(2) at least one superconductive main coil positioned around said first axis and carrying a first main electric current in a first direction; and
(3) a first vacuum enclosure enclosing said at least one superconductive main coil of said first assembly;
(b) a second assembly longitudinally spaced apart from and disposed below said first assembly, comprising:
(1) a longitudinally-extending second axis generally coaxially aligned with said first axis;
(2) at least one superconductive main coil positioned around said second axis and carrying a second main electric current in said first direction; and
(3) a second vacuum enclosure enclosing said at least one superconductive main coil of second assembly;
(c) at least one support beam external to said first and second vacuum enclosures having a first end attached to said first assembly and having a second end attached to said second assembly.
29. The open MRI system of claim 23, wherein:
the vibration isolation system is secured to a floor and the MRI magnet system is attached over the vibration isolation system; and
the vibration isolation system is configured within a footprint of the MRI magnet system.
30. The open MRI system of claim 23, wherein the vibration isolation system comprises a material which is capable of isolating vibration from the environment.
31. The open MRI system of claim 30, wherein the vibration isolation system comprises a rubber mat or rubber blocks placed between the magnet system and a floor.
32. The open MRI system of claim 23, wherein the magnet system is arranged in a clam-shell configuration.
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 method of treating the exhaust gas stream flowing from a vehicle internal combustion engine during a period following a cold-start of the engine, the exhaust gas stream comprising a mixture of nitric oxide, carbon monoxide, hydrocarbons, hydrogen, water, carbon dioxide, oxygen, and nitrogen, the exhaust gas stream being at an initial temperature below about 75\xb0 C. and progressively warming during further engine operation, the method comprising;
continually passing the hydrogen, oxygen, and nitric oxide-containing exhaust gas stream in contact with a silveralumina particulate catalyst to oxidize at least a portion of the nitric oxide to nitrogen dioxide and to temporarily store some of the nitrogen oxide and nitrogen dioxide product on the particulate catalyst material, the silveralumina particulate catalyst consisting essentially of particles of silver or silver oxide deposited on carrier particles of alumina; then, continually
passing the exhaust gas stream into contact with at least one downstream catalytic material for further oxidation of nitric oxide or for reduction of nitric oxide and nitrogen dioxide as the exhaust gas increases in temperature and heats each such downstream reactor to an operating temperature; and
continuing the passage of the exhaust gas through each reactor during the duration of engine operation, while stored material is removed from the silveralumina particulate catalyst and the silveralumina particulate catalyst ceases its affect on the warmed exhaust gas stream until the engine is stopped and started again, following an engine cool-down period.
2. A method of treating the exhaust from a vehicle internal combustion engine as recited in claim 1 in which the silveralumina catalyst consists essentially of particles of silver or a silver oxide deposited on carrier particles of alumina and the silver content is in the range of 0.5% to 10% of the total of the particles of silver or silver oxide and alumina.
3. A method of treating the exhaust from a vehicle internal combustion engine as recited in claim 1 in which the hydrogen and nitric oxide-containing exhaust is passed in contact with the silveralumina particulate catalyst and then with a different oxidation catalyst for NO, which oxidation catalyst is composed to commence oxidation of NO at temperatures of about 190\xb0 C. or higher.
4. A method of treating the exhaust from a vehicle internal combustion engine as recited in claim 3 in which the different oxidation catalyst for NO comprises a platinum group metal.
5. A method of treating the exhaust from a vehicle internal combustion engine as recited in claim 1 in which the silveralumina particulate catalyst is located so that exhaust gas exits an exhaust manifold of the engine in a defined exhaust gas flow path and flows into contact with the silveralumina catalyst after flowing no more than about fifty centimeters distance along the flow path after leaving the exhaust manifold.
6. A method of treating the exhaust from a vehicle internal combustion engine as recited in claim 1 in which the vehicle internal combustion engine is a diesel engine which is controlled to operate at an air-to-fuel ratio of about 17:1 during a major portion of its operation.
7. A method of treating the exhaust from a vehicle internal combustion engine as recited in claim 1 in which the silveralumina particulate catalyst is deposited as wash coat layers on the wall surfaces of parallel open-ended channels in an monolithic body, the parallel open-ended channels extending from an exhaust gas flow inlet to an exhaust gas flow outlet of the monolithic body.
8. A method of treating the exhaust from a vehicle internal combustion engine as recited in claim 7 in which the silveralumina particulate catalyst is deposited as wash coat layers on the wall surfaces of parallel open-ended channels in an monolithic body at the gas flow inlet end of the body and particles of an oxidation catalyst comprising particles of a platinum group metal are deposited as a wash coat on the wall surfaces of parallel open-ended channels at the gas flow outlet end of the body.
9. A method of treating the exhaust from a vehicle internal combustion engine as recited in claim 7 in which particles of an oxidation catalyst comprising particles of a platinum group metal are deposited as a wash coat on the wall surfaces of parallel open-ended channels, the wash coat of platinum group metal extending on the wall surfaces from the exhaust gas flow inlet of the body to its exhaust gas flow outlet, and in which particles of the silveralumina particulate catalyst are deposited as a wash coat overlying the wash coat particles of the platinum group metal.
10. A method of treating the exhaust from a vehicle internal combustion engine as recited in claim 1 in which the hydrogen content of the total exhaust gas stream is in the range of about 100 ppm to about 1000 ppm during a period following the cold start of the engine.
11. A method of treating the exhaust gas stream flowing from a vehicle internal combustion engine during a period following a cold-start of the engine, the engine being operated in a lean-burn mode during the cold start, the exhaust gas stream comprising a mixture of nitric oxide, carbon monoxide, hydrocarbons, hydrogen, water, carbon dioxide, oxygen, and nitrogen, the exhaust gas stream being at an initial temperature below about 75\xb0 C. and progressively warming during further engine operation, the method comprising;
continually passing the hydrogen, oxygen, and nitric oxide-containing exhaust gas stream in contact with a silveralumina particulate catalyst to oxidize at least a portion of the nitric oxide to nitrogen dioxide and to temporarily store some of the nitrogen oxide and nitrogen dioxide product on the particulate catalyst material, the silveralumina particulate catalyst being the first catalyst material contacted by the flowing exhaust gas stream, the silveralumina catalyst consisting essentially of particles of silver or a silver oxide deposited on carrier particles of alumina, the silver content being in the range of 0.5% to 10% of the total of the particles of silver or silver oxide and alumina; then, immediately and continually
passing the exhaust gas stream into contact with a catalytic material comprising particles of one or more platinum group metals for oxidation of nitric oxide as the exhaust gas increases in temperature and heats the platinum group metal catalyst to an operating temperature; and
continuing the passage of the exhaust gas into contact with each of the silveralumina catalyst and the particles of platinum group metal for the duration of engine operation, while stored material is removed from the silveralumina particulate catalyst and the silveralumina particulate catalyst ceases its affect on the warmed exhaust gas stream when it has reached at temperature of about 250\xb0 C. or lower and until the engine is stopped and started again, following an engine cool-down period.
12. A method of treating the exhaust from a vehicle internal combustion engine as recited in claim 11 in which the silveralumina particulate catalyst is located so that exhaust gas exits an exhaust manifold of the engine in a defined exhaust gas flow path and flows into contact with the silveralumina catalyst after flowing no more than about fifty centimeters distance along the flow path after leaving the exhaust manifold.
13. A method of treating the exhaust from a vehicle internal combustion engine as recited in claim 11 in which the hydrogen content of the total exhaust gas stream is in the range of about 100 ppm to about 1000 ppm during a period following the cold start of the engine.
14. A method of treating the exhaust from a vehicle internal combustion engine as recited in claim 11 in which the vehicle internal combustion engine is a diesel engine which is controlled to operate at an air-to-fuel ratio of about 17:1 during a major portion of its operation.
15. A method of treating the exhaust from a vehicle internal combustion engine as recited in claim 11 in which the silveralumina particulate catalyst is deposited as wash coat layers on the wall surfaces of parallel open-ended channels in an monolithic body, the parallel open-ended channels extending from an exhaust gas flow inlet to an exhaust gas flow outlet of the monolithic body.
16. A method of treating the exhaust gas stream as recited in claim 11 in which the exhaust gas stream passing from the particles of platinum group metal catalyst particles is then subjected to a catalyzed reduction reaction to reduce nitrogen oxides to nitrogen.
17. A method of treating the exhaust from a vehicle internal combustion engine as recited in claim 15 in which the silveralumina particulate catalyst is deposited as wash coat layers on the wall surfaces of parallel open-ended channels in an monolithic body at the gas flow inlet end of the body and particles of an oxidation catalyst comprising particles of a platinum group metal are deposited as a wash coat on the wall surfaces of parallel open-ended channels at the gas flow outlet end of the body.
18. A method of treating the exhaust from a vehicle internal combustion engine as recited in claim 15 in which particles of an oxidation catalyst comprising particles of a platinum group metal are deposited as a wash coat on the wall surfaces of parallel open-ended channels, the wash coat of platinum group metal extending on the wall surfaces from the exhaust gas flow inlet of the body to its exhaust gas flow outlet, and in which particles of the silveralumina particulate catalyst are deposited as a wash coat overlying the wash coat particles of the platinum group metal.
19. A catalytic reactor for the treatment of the exhaust gas stream from a lean-burn, hydrocarbon-fueled, internal combustion engine following a cold start of the engine, the exhaust gas stream being expelled from the engine through an exhaust gas exit and, following a cold start, comprising a mixture of nitric oxide, carbon monoxide, hydrocarbons, hydrogen, water, carbon dioxide, oxygen, and nitrogen, the exhaust gas stream being at an initial temperature below about 75\xb0 C. upon the cold start and progressively warming during further engine operation; the catalytic reactor consisting essentially of particles of silver or a silver oxide deposited on carrier particles of alumina and the silver content being in the range of 0.5% to 10% of the total of the particles of silver or silver oxide and alumina.
20. A catalytic reactor as recited in claim 19 adapted for location so that exhaust gas exits the engine in a defined exhaust gas flow path and flows into contact with the silveralumina catalyst after flowing no more than about fifty centimeters distance along the flow path after leaving the exhaust manifold.