We claim:
1. A dual coil system for magnetic resonance imaging, the system comprising:
a surface coil;
a volume coil having a cylindrical non-magnetic core module having an outer surface and a longitudinal axis, a cylindrical bore extending through the core module along the longitudinal axis and defining an inner surface; a plurality of conductive strip lines, the strip lines extending parallel to the longitudinal axis on the inner surface of the core module; a pair of circuit boards carried at the ends of the core module; and a plurality of resonating elements, each of the resonating elements including one of the strip lines and at lease one tuneable capacitor.
2. The dual system of claim 1 further comprising a transceiver unit having a RF transmitter and a RF receiver, the transceiver unit connected to the surface coil and the volume coil.
3. The dual coil system of claim 2 wherein the volume coil further comprises a plurality of shielding strips extending parallel to the longitudinal axis on the outer suface of the core module and wherein the adjacent shielding strips are connected by at least one capacitor attaching adjacent shielding strips at alternative ends of the shielding strips.
4. The dual coil system of claim 3 wherein the core module of the volume coil is formed of a dielectric material and the strip lines of the volume coil are electroplated on the core module.
5. The dual coil system of claim 4 further comprising a matching circuit for adjusting the impedance of the resonating elements to that of the RF source and a filter for separating the high frequency RF signal from interfering with the DC tuningdetuning signal.
6. The dual coil system of claim 4 wherein both the surface coil and volume coil have a detuning circuit for detuning the resonating element and a RF decoupling circuit for reducing interference between a DC detuning signal and a RF signal.
7. The dual coil system of claim 4 wherein the surface coil comprises a single loop or a dome shaped coil having a curvilinear surface.
8. A surface coil comprising;
a curvilinear support surface having a concave inner surface and a convex outer surface;
a circuit board assembly;
at least a pair of conductive strips carried on the concave inner surface;
at least one capacitor connecting the conductive strips; and
a tuneable variable capacitor.
9. The surface coil of claim 8 wherein there are at least four conductive strips carried on the concave inner surface and further comprising a resonating element including one of the conductive strips on the concave inner surface, and a shielding strip on the convex outer surface.
10. The surface coil of claim 9 further comprising:
a detuning circuit for detuning the resonating elements;
a RF decoupling circuit for reducing interference between a C detuning signal and an RF signal; and
a matching circuit for adjusting the impedance of the resonating elements to that of a RF source.
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. An impressed current cathodic protection system for a marine engine having a wall that forms a coolant passage, the coolant passage being configured to receive a conductive coolant, the system comprising:
a plurality of electrodes, at least a portion of each electrode being disposed in the coolant passage, each electrode being electrically insulated from the wall;
a power supply configured to provide a protective current between the plurality of electrodes and the engine via the conductive coolant; and
an electrical conductor insulated from the engine and the conductive coolant, said conductor electrically coupling the power supply to at least two of said plurality of electrodes, said coupling occurring at a point insulated from the conductive coolant.
2. The system according to claim 1, wherein the power supply device comprises a controller regulating the protective current so as to generally maintain a potential difference between the electrodes and the engine.
3. The system according to claim 1, wherein at least one of the plurality of electrodes has a linear form.
4. The system according to claim 3, wherein the shape of each of the electrodes generally conforms to a shape of a section of the coolant passage in which such electrode is disposed.
5. The system according to claim 1, wherein at least one of the plurality of electrodes has a loop form.
6. The system according to claim 1, wherein at least one of each of electrodes is connected to the power supply.
7. The system according to claim 1, wherein the plurality of electrodes is arranged side by side,
8. The system according to claim 1, wherein the power supply comprises a circuit for automatically shutting off one of the plurality of electrodes upon the occurrence of a short circuit to the one of the plurality of electrodes.
9. The system according to claim 1, wherein the power supply comprises a switch disconnecting power to the electrode when the engine is stopped.
10. The system according to claim 1, further comprising:
an abnormality detection circuit for detecting an abnormality in the power supply to the plurality of electrodes; and
an alarm circuit for producing an alarm in response to the detection of an abnormality.
11. A marine engine comprising:
a wall forming a coolant passage configured to receive a conductive coolant;
a plurality of electrodes, at least a portion of each electrode being disposed in the coolant passage, each electrode being electrically insulated from the wall;
a power supply configured to supply an electric potential between the plurality of electrodes and the engine; and
an electrical conductor insulated from the engine and the conductive coolant, said conductor electrically coupling the power supply to at least two of said plurality of electrodes, said coupling occurring outside the coolant passage.
12. The marine engine according to claim 11, wherein the plurality of electrodes is configured to provide a protective current to the engine via the conductive coolant, and wherein the power supply is configured to control the protective current so as to generally maintain the electric potential between the plurality of electrodes and the engine.
13. The marine engine according to claim 12, wherein the plurality of electrodes provide the protective current through a wall of the coolant passage in the engine.
14. The marine engine according to claim 12 further comprising a reference electrode, wherein the power supply is configured to control the protective current so as to generally maintain the electric potential between the plurality of electrodes and the engine based at least in part on a measured potential between the reference electrode and the engine.
15. The marine engine according to claim 11, wherein a shape of at least one of the plurality of electrodes generally conforms to a shape of a portion of the coolant passage in which such electrode is disposed.
16. The marine engine according to claim 11 further comprising a shut-off circuit configured to shut off the electric potential in response to at least one of the plurality of electrodes short circuiting.
17. The marine engine according to claim 11, further comprising an abnormality detection circuit configured to detect abnormalities in the electric potential.
18. The marine engine according to claim 11, wherein the power supply is configured to generally maintain a constant voltage between the plurality of electrodes and the engine.
19. The marine engine according to claim 11, wherein the power supply is configured to generally maintain a constant current between the plurality of electrodes and the engine.
20. The marine engine according to claim 11 additionally having a crankshaft oriented to rotate about a generally vertical axis.