1-7. (canceled)
8. A method for cleaning an outer surface arranged at the bottom of a tank, a vessel or a similar enclosure, comprising:
generating and supplying a pressurized cleaning fluid from a production source of pressurized cleaning fluid, the fluid pressure being between 3 and 12 bar;
conveying the cleaning fluid opposite the outer surface of the tank by circulating the fluid in a pipe network arranged below the tank;
cleaning the outer surface of the tank using a plurality of rotating jets of cleaning fluid, the plurality of jets being generated by at least one multi jet rotating head connected to the pipe network;
wherein the conveying of the cleaning fluid is realized by the pipe network forming a closed loop arranged below and near the center of the outer surface of the tank, the closed loop being supplied with cleaning fluid by a feed pipe connected to the production source of pressurized cleaning fluid.
9. The method according to claim 8, wherein the pipe network comprises a plurality of pipes emerging radially from the closed loop.
10. The method according to claim 9, wherein each pipe is straight and comprises a free end arranged near a periphery of the outer surface.
11. The method according to claim 8, wherein the pipe network and the at least one multi jet rotating head are each made from a stainless steel.
12. The method according to claim 8, wherein the pressure of the cleaning fluid is between 8 and 10 bar.
13. The method according to claim 8, wherein the cleaning fluid is water.
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 Luneberg lens having a single-layer structure or a multilayer structure containing a plurality of layers having different dielectric constants, wherein the respective structure is produced by mixing a polyolefin resin andor a derivative thereof with an inorganic filler having a high dielectric constant, the volume ratio of the polyolefin resin andor the derivative thereof to the filler being 99 to 50:1 to 50, adding a foaming agent to the resulting resin mixture and then performing preliminary expansion, and molding the resulting pre-expanded beads; and wherein at least a foamed dielectric layer having a dielectric constant of 1.5 or more is formed using the pre-expanded beads that have been subjected to classification and selection such that f(A) satisfies the expression 0.0005\u2266f(A)\u22660.1, where f(A) is represented by the equation: f(A)=\u03c3aAave, \u03c3a is the deviation of a gas volume fraction Ar in the foamed dielectric layer, and Aave is the average of the gas volume fractions Ars at positions in the foamed dielectric layer.
2. The Luneberg lens according to claim 1, wherein the inorganic filler having a high dielectric constant comprises titanium oxide, a titanate, a zirconate, or a mixture thereof.
3. The Luneberg lens according to claim 2, wherein the titanate is barium titanate, strontium titanate, calcium titanate, or magnesium titanate.
4. The Luneberg lens according to claim 1 or 2, wherein the foamed dielectric layer having a dielectric constant of 1.5 or more is formed using the pre-expanded beads classified by gravity separation or size classification.
5. A method of producing a Luneberg lens that satisfies the requirements described in claim 1, comprising the steps of:
mixing a polyolefin resin andor a derivative thereof with an inorganic filler having a high dielectric constant, the volume ratio of the polyolefin resin andor the derivative thereof to the filler being 99 to 50:1 to 50;
adding a foaming agent to the resulting resin mixture and then performing pre-expansion;
classifying and selecting the resulting pre-expanded beads by gravity separation or size classification; and
forming the classified and selected pre-expanded beads into a shape.