AU2005200784B2

AU2005200784B2 - Drag-head and hopper dredger

Info

Publication number: AU2005200784B2
Application number: AU2005200784A
Authority: AU
Inventors: Etienne Marie Clymans; Jan Gabriel
Original assignee: DREDECO Pty Ltd
Current assignee: DREDECO Pty Ltd
Priority date: 2004-02-19
Filing date: 2005-02-21
Publication date: 2010-12-23
Anticipated expiration: 2025-02-21
Also published as: AU2005200784A1; BE1015911A3

Description

AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT ORIGINAL Name of Applicant: Dredeco Pty Ltd. Actual Inventors: Etienne Marie Clymans and Jan Gabriel Address for Service is: SHELSTON IP 60 Margaret Street Telephone No: (02) 9777 1111 SYDNEY NSW 2000 Facsimile No. (02) 9241 4666 CCN: 3710000352 Attorney Code: SW Invention Title: DRAG-HEAD AND HOPPER DREDGER The following statement is a full description of this invention, including the best method of performing it known to us: File: 45258AUP00 la DRAG-HEAD AND HOPPER DREDGER FIELD OF THE INVENTION The present invention relates to a drag-head for a suction dredging 5 apparatus for cutting and sucking up dredging material. The invention further relates to a hopper dredger provided with at least one suction pipe onto which a drag-head is fitted. BACKGROUND OF THE INVENTION 10 Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field. Drag-heads for a suction dredging apparatus for cutting and sucking up dredging material may comprise a housing that is provided on its underside with an 15 inlet opening through which dredging material can be sucked, and means of cutting in the vicinity of the inlet opening. Such a drag-head is generally known and is typically used in a hopper dredger for dredging soft material, such as sand. Among others, a hopper dredger has the advantage that it is possible to work in relatively poor weather and/or sea 20 conditions (high waves, strong currents) and that other vessels are not appreciably impeded. The disadvantage of a hopper dredger is that it is not suitable for dredging hard material. Typically a cutter dredger is used for dredging hard material, but a cutter dredger is susceptible to strong currents and high waves, and consequently less suitable for working in difficult sea conditions (waves, wind, 25 current). NL 1020521 relates to a drag-head dredger for dredging sand or layers of silt from a water bed. The drag-head is provided with a bottom edge, which rests on the water bed surface. This bottom edge is shaped in such a way that the drag-head does not dig into the bed but does cut through raised parts. 30 In addition it forms a good closure with the bed surface. The bed material is loosened with the help of water jets. The loosened material is removed via intake openings. The force with which the suction head presses onto the water 2 bed as a result of the weight of the suction pipe is then more than sufficient to neutralise the lifting forces. A problem of this trailing suction dredger is its unsuitability for hard material. Noted from GB 1312032 is a hopper dredger with a drag-head, which is 5 provided with means of cutting, which are mounted in an area below the centre of gravity of the suction intake. This has the effect of somewhat increasing the scraping force on the bed. There is no excessive increase in weight. From US 5488229 an excavating head is known, which uses water jets to loosen the bed. A vacuum is used to remove the bed. The weight of the excavating 10 head is sufficient to hold the excavating head closely onto the excavation surface. However, this is not a drag-head for a suction dredging apparatus. FR 1501273 and FR 1323429 relate to other dredging apparatuses in which the weight of the suction pipe plays a part or in which the turning of the carrier of the means of cutting allows the force exerted on the means of cutting to increase. 15 However, neither of these documents speaks of the drag-head itself being made excessively heavier. It is an object of the present invention in at least one preferred form to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. 20 Advantageously, the invention, in at least one preferred form, provides a drag-head and hopper dredger, which is suitable for dredging harder material than is usual in the industry at the moment. SUMMARY OF THE INVENTION 25 According to a first aspect of the invention there is provided a passive drag head for a suction dredging apparatus for cutting and sucking up dredging material by dragging the drag-head in a direction of trailing across a hard bed of dredging material, said passive drag-head comprising: a housing that on its underside is provided with an inlet opening through 30 which dredging material can be sucked; said housing comprising as seen in the direction of trailing, behind the inlet opening, a front edge and before the inlet opening, a reinforced heel part adapted to contact the hard bed of dredging 3 material in operation; said front edge and said heel part delimiting the inlet opening; and cutting means in the vicinity of the inlet opening, wherein the cutting means are cutting teeth mounted on an elongate 5 carrier, which elongate carrier is mounted on said front edgie, wherein the drag-head is made excessively heavy for the teeth to exert a sufficiently high tractive force and penetration force on the dredging material by the cutting teeth to cut the hard bed of the dredging material. Unless the context clearly requires otherwise, throughout the description 10 and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to". Making the drag-head excessively heavy advantageously results in an extra penetration force being exerted on the material, which can be comparable to 15 the force exerted by a cutter head of a cutter dredger. This creates a drag-head, which breaks the bond of 'hard' bed by exerting a very high penetration force. In a preferred embodiment teeth are used for the means of cutting. This results in further localisation of the forces. The high force is obtained precisely by making the drag-head heavier. 20 By way of illustration an example is given below of the forces exerted by a cutter dredger compared to the forces exerted by a hopper dredger with a drag head in accordance with the invention. Cutter dredger: 25 - mass of ladder + cutter: approximately 2500 kN; - cutting force of cutter drive: approximately 1000 kN; - number of active teeth: 5 to 10; Hopper dredger: - tractive force: approximately 1100 kN; 4 - mass of the heavier drag-head (+ possible mass of part of bottom pipe compensation for any swell compensator + compensation for pressure difference across the drag-head): approximately 900 kN; - number of active teeth: 6. 5 Thus by reducing the number of teeth, penetration forces can be attained which are comparable to those of cutter dredgers. Themaximum cutting thickness to which it is possible to work with such a drag-head will be dependent on the type of bed. In accordance with a preferred embodiment the drag-head is made 10 excessively heavy such that it is suitable for hard dredging material, such as rock, especially for dredging material with unconfined compressive strength (USC) up to approximately 10 MPa. For example with such a drag-head it will be possible to achieve cutting thicknesses of 50 mm for hard dredging material (UCS up to 10 MPa) and up to 150 mm for softer dredging material. 15 The housing preferably comprises a fixed housing part and a visor mounted so that it is free to swivel relative to that fixed housing part. In this way the angle of the visor can be adjusted relative to the bed being dredged, whereby the fixed housing part is coupled to a suction pipe of a hopper dredger and the visor can be turned to a limited extent relative to the face of the suction pipe. 20 In accordance with a possible embodiment, for positioning the visor relative to the fixed housing part, at least one piston cylinder assembly is mounted between the visor and the fixed housing part. This piston cylinder assembly can then be operated by means of suitable means of control from the aft deckhouse of a hopper dredger. 25 In accordance with the preferred embodiment the means of cutting are cutting teeth mounted on a carrier, which carrier is placed close to the inlet opening. This carrier is for example a beam-shaped carrier in which a number of cutting teeth, for example cutting teeth of the make Vosta, type 65D, are mounted interchangeably. Preferably the carrier, as seen in the direction of 30 trailing, is mounted behind the inlet opening, on its edge. In accordance with a further developed embodiment, the carrier is provided on the side of the teeth facing away from the inlet opening with means of sealing, 5 such as a flexible flap, which press against the bed during operation. In this way the amount of water, which is sucked up between the cutting teeth, is reduced, and the pressure difference across the visor and thus the penetration force is additionally increased. Instead of a flexible flap, steel plates hinging around a 5 horizontal shaft can also be fitted, which, seen in the direction of trailing, hang behind the cutting teeth. Furthermore, means of adjustment are preferably provided for adjusting the position of the cutting teeth. In this way the teeth can be brought into a suitable position according to the desired cutting thickness and the type of dredging 10 material. The means of adjustment are for example at least one piston cylinder assembly mounted between the housing and the means of cutting. In accordance with a possible embodiment the carrier of the cutting teeth is mounted so that it is free to swivel relative to the housing, and the piston cylinder assembly is mounted between the carrier and the housing. In the embodiment with 15 visor the carrier will typically be mounted so that it is free to swivel relative to the visor. The piston cylinder assembly for positioning the means of cutting can be further provided with a protection system for limiting the pressure in the cylinder of the piston cylinder assembly. The pressure in the cylinder will usually be a good 20 measure for the axial loading of the suction pipe, and with the help of such a protection system it is possible to prevent excessively high loadings of the suction pipe occurring. In accordance with a possible embodiment the protection system comprises an overpressure valve and a buffer tank, which overpressure valve is coupled by 25 its pressure side to the cylinder and its other side emerges in the buffer tank. Finally the housing usually comprises a grid that extends essentially across a cross-section of the housing in order to prevent pieces with too great a diameter being dragged along into the suction pipe and blocking the pump. According to second aspect of the invention there is provided a hopper 30 dredger comprising at least one suction pipe on which a drag-head according to the first aspect of the invention is mounted.

5a According to another aspect of the invention there is provided a hopper dredger comprising at least one suction pipe on which a drag-head according to the first aspect is mounted, wherein a protection system is provided for limiting the axial loading of the suction pipe, wherein the housing comprises a fixed housing 5 part and a visor mounted so that it is free to swivel relative to that fixed housing part, wherein at least one piston cylinder assembly is mounted between the visor and the fixed housing part for positioning the visor relative to the fixed housing part, wherein the protection system comprises a sensor system for detecting cylinder fluid in the buffer tank, and wherein the hopper dredger is provided with 10 control means for the at least one piston cylinder assembly for positioning the visor, which sensor system is linked to the control means. Preferably at least one suction pipe has its bottom end made with a thickened wall for obtaining additional mass, which is concentrated around the suspension point at this bottom end. In this way the behaviour of the suction pipe 15 is comparable with the behaviour of a suction pipe without thickened walls, and the only effect of making this heavier will be that an extra penetration force of the teeth is obtained. Because the mass is concentrated close to the suspension point, 6 this will especially have no effect on the swaying behaviour as the suction pipe is being hoisted aboard or lowered overboard. In accordance with a preferred embodiment a protection system is provided for limiting the axial loading of the suction pipe. Preferably the protection system 5 comprises the protection system described above and a sensor system for detecting cylinder fluid in the buffer tank, whereby the hopper dredger is provided with means of control for the piston cylinder assembly for positioning the visor, which sensor system is linked to the means of control. If the overpressure valve of the tooth cylinder opens, and the buffer tank fills, this is detected, whereupon 10 the visor cylinder retracts. This makes the teeth withdraw quickly from the bed, and the axial loading of the suction pipe will fall quickly and damage will be prevented. Once the visor cylinder retracts, it and the tooth cylinder are sent back out to the start position. The rip process is thereby as it were automatically resumed. 15 In accordance with a further developed embodiment variant the hopper dredger is provided with a first winch with a hoisting cable for hoisting and lowering the suction pipe, whereby the bottom end of the suction pipe is provided with a guide pulley for the hoisting cable in order to halve the loading of that first winch. The end of the hoisting cable led over the guide pulley can be coupled to a 20 second winch, in such a way that the hoisting speed of a system without guide pulley is maintained. Furthermore, a swell compensator can be placed between each winch and the guide pulley for compensating the vertical movements of the ship. For an existing trailing hopper dredger with a suction pipe on each side, this embodiment 25 offers the significant advantage that the swell compensator and the suction intake winch on the side where the tube is not being used can now be deployed with as great advantage almost doubled hoisting capacity while maintaining the hoisting speed and the swell compensation characteristics. 30 BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: 7 Figures 1, 2 and 3 show top, side, and rear views respectively of a possible embodiment of a hopper dredger in accordance with the invention, whereby the suction pipe is shown in different positions; Figures 4, 5, and 6 each show a perspective view, seen at different angles, 5 of a possible embodiment of a drag-head in accordance with the invention; and Figure 7 shows a side view of the embodiment of figures 4-6. PREFERRED EMBODIMENTS OF THE INVENTION First the general components of the hopper dredger of figures 1-3 will be 10 described. A hopper dredger 1 is a ship that is suitable for fully loading a hopper space 5 with dredging material by means of pumping while the ship is sailing in a particular direction. The ship is provided with a suction pipe 2, which on its end is provided with a drag-head 3 and consists of a bottom and a top pipe, which are coupled together by means of a flexible connector 4. The suction pipe can be 15 raised or lowered with the help of derrick 10 and winches 8, 8', as will be further described in more detail. Furthermore, in figures 1-3 it is possible to distinguish an aft deckhouse 6 and a deck crane 7. Now a robust preferred embodiment of the drag-head in accordance with the invention will be described with reference to figures 4-7. 20 In the embodiment shown drag-head 3 comprises a housing that can be coupled to suction pipe 2 and consisting of a fixed housing part 20 and a moveable visor 21. This visor 21 is mounted so that it can hinge around an axis 23, and the position of the visor can be adjusted with the help of a piston cylinder assembly 24, piston 25 of which is coupled free to hinge with the visor, and cylinder housing 25 26 is coupled free to hinge with housing 20. Drag-head 3 is further provided with a carrier beam 27 placed at the bottom edge of visor 20 in which a number of cutting teeth 28 are mounted. This carrier beam 27 is mounted so that it is free to swivel around an axis 29, and the position of carrier beam 27 can be adjusted by a piston cylinder assembly 30, piston 32 of 30 which is coupled free to hinge with carrier beam 27 and cylinder housing 31 is coupled free to hinge with visor 21. Piston cylinder assembly 24 for positioning the visor, and piston cylinder assembly 30 for positioning the cutting teeth are both placed centrally on the top of 8 the drag-head, so that the risk of its different components becoming damaged by contact with the bed, and especially pistons 25, 32 and the hydraulic pipes, is reduced. The position of visor 21 can be expressed with the help of the angle through which visor 21 is turned relative to housing 20, and hereinafter this angle 5 will be referred to as the visor angle. Analogously the position of carrier beam 27 can be expressed with the help of the angle through which carrier beam 27 is turned relative to visor 21, and hereinafter this angle will be referred to as the cutting angle. Piston cylinder assemblies 24, 30 are controlled from aft deckhouse 6 for adjusting the visor and cutting angles. 10 The hydraulic control system of cylinders 24, 30 can be further provided with a protective switching arrangement for preventing excessive axial loading of the trailing pipe. The moment of carrier beam 27 around axis 29, and thus the pressure in cylinder housing 31 is a good measure for the axial force in the suction pipe, because essentially the angle of the suction pipe to the bed remains 15 constant, and this forms the underlying notion behind the protective switching arrangement described in the following. The protective switching arrangement comprises an overflow valve switched between the bottom of cylinder housing 31 and a buffer tank. The system further comprises a sensor system for detecting the presence of hydraulic oil in the buffer tank. 20 Whenever the sum of the forces on cutting teeth 28 exceeds a threshold value determined by the overflow valve, the hydraulic oil can flow through the valve to the buffer tank. Due to the tractive forces and the speed of the ship carrier beam 27 will turn away from the direction of travel, so that the hydraulic oil will be forced from the cylinder bottom to the buffer tank. The sensor system will detect 25 this and transmit an appropriate signal to the means of control of visor positioning cylinder 24 in order likewise to raise the visor. Once the visor has fully retracted, carrier beam 27 can turn back to its preset position, and the hydraulic oil runs back from the buffer tank to cylinder housing 31. Thus with the help of the protective system the suction pipe is protected against excessive tensile strains, whereby 30 following every intervention by the protective system the drag-head can be used again normally. Cutting teeth 28 are for example Vosta, type 65D cutting teeth, which are typically used in cutting dredgers for working in rocky ground. Hardened steel 9 slide blocks 37 can be provided on both sides of each cutting tooth. When the tip of the teeth is sufficiently retracted between a pair of slide blocks 37, then the drag head will skim across the bed on slide blocks 37 and the slide blocks (not shown) at heel 34. 5 In the embodiment shown the underside of fixed housing part 20 is provided with a plough 33 (figure 5). In order to protect heel 34 of housing part 20, hardened steel slide blocks (not shown) can be placed on heel 34. Furthermore, a grid 35 is placed in housing part 20 in order to stop large pieces of debris being sucked in and blocking the pump. 10 Carrier beam 27 can be further provided with a flexible flap 36. Especially in the case of small cutting thicknesses, this prevents too much water being sucked up between the teeth. As a consequence the pressure difference across visor 21 increases and thus also the penetration force of the cutting teeth. To obtain a suitable, robust drag-head 3 it must be made to be compact 15 and heavy. However, it is advantageous not to make the weight of drag-head 3 any heavier than the maximum carrying capacity of deck crane 7. Among other things this means that the wall thicknesses of the different components will be greater than for a normal drag-head. The wall thicknesses can vary for example between 30 and 80 mm, and the drag-head can possibly be fabricated as a forging. 20 In the example of a 2 m wide drag-head, the drag-head will have for example a weight of approximately 32 tons. Furthermore, the bottom pipe of the suction pipe is made heavier compared to a normal suction pipe of a hopper dredger. At bottom end 12 of the lowest suction pipe this mass is concentrated by making it with a thicker wall at that end 25 12. Here the thickness of the wall can be for example 300 mm, so that an additional mass of approximately 50 tons is obtained for a suction pipe with a diameter of approximately 1.2 m. This greater mass would mean that the loading of derrick 10 and of winch 8 is increased. In order to halve the loading of winches 8, 8', a pulley 9 is attached 30 to the lowest suction pipe. However, this also halves the hoisting speed and the range and speed of swell compensator 18. This can be rectified by mounting an additional pulley 13 in derrick 10 and to lead the cable via three pulleys 14, 15, 16 to the other side of the ship, in the example, to port. There the cable is wound onto 10 winch 8' to port via swell compensator 18'. Winches 8, 8' and swell compensators 18, 18' to port and starboard work in parallel, and the hoisting speed of the suction pipe and the speed and range of the swell compensators are no longer halved. For transporting larger pieces of rock debris it is advantageous to have a relatively 5 high flow rate in a relatively small drag-head. The internal diameter of the suction pipe is for example approximately 1.2 m for a drag-head with a width of approximately 2 m. The functioning of the hopper dredger in accordance with the invention is described in the following. On arrival at the dredging location suction pipe 2 is 10 lowered with visor 21 in the retracted position until reinforced heel 34 of fixed housing part 20 makes contact with the bed, whereby the contact is detected by the swell compensator (spring is no longer in the compressed position). Next the water depth is sounded and the angle which suction pipe 2 is making to the bed is calculated from this. The visor angle for which the cutting teeth just touch the 15 bed can be deduced from this angle. This visor angle is called the zero angle (angle for which the cutting thickness is zero). The visor can now be brought into a position which corresponds with zero angle plus a so-called "rip angle" which corresponds with the desired cutting thickness. At the moment when cutting teeth 28 make contact with the bed, the pressure in cylinders 30, 24 will rise 20 considerably. The cutting angle at which the cutting teeth penetrate the bed can be further adjusted by cylinder 30. The rip and cutting angles will be chosen according to the material being dredged. Now the actual dredging can begin. Note further that the pressure difference across drag-head 3 will increase when visor 21 is moved downward, and that from this pressure difference it can usually be 25 deduced whether teeth 28 are penetrating the bed sufficiently and whether heel 34 is not being lifted off the bed. It will be evident to the specialist that many modifications can be made to the examples illustrated above. For instance the hopper dredger in the drawings is an existing hopper, which is converted into a hopper dredger in accordance 30 with the present invention, but in the event that a new hopper dredger were to be built in accordance with the invention, it will be evident to the specialist that certain components could be designed to be more efficient.

Claims

1. A passive drag-head for a suction dredging apparatus for cutting and sucking up dredging material by dragging the drag-head in a direction of trailing 5 across a hard bed of dredging material, said passive drag-head comprising: a housing that on its underside is provided with an inlet opening through which dredging material can be sucked; said housing comprising as seen in the direction of trailing, behind the inlet opening, a front edge and before the inlet opening, a reinforced heel part adapted to contact the hard bed of dredging 10 material in operation, said front edge and said heel part delimiting the inlet opening, and cutting means in the vicinity of the inlet opening, wherein the cutting means are cutting teeth mounted on an elongate carrier, which elongate carrier is mounted on said front edge, 15 wherein the drag-head is made excessively heavy for the teeth to exert a sufficiently high tractive force and penetration force on the dredging material by the cutting teeth to cut the hard bed of the dredging material.

2. A drag-head according to claim 1, wherein the drag-head is made 20 excessively heavy such that it is suitable for hard dredging material, such as rock, with an unconfined compressive strength (USC) of up to approximately 10 MPa.

3. A drag-head according to any one of the preceding claims, wherein the housing comprises a fixed housing part comprising said reinforced heel part; and a 25 visor mounted so that it is free to swivel relative to that fixed housing part, said visor comprising said front edge.

4. A drag-head according to claim 3, wherein at least one piston cylinder assembly is mounted between the visor and the fixed housing part for positioning 30 the visor relative to the fixed housing part. 12

5. A drag-head according to any one of the preceding claims, wherein the elongate carrier is provided on the side of the teeth facing away from the inlet opening with means of sealing which press against the bed during operation. 5

6. A drag-head according to claim 5, wherein the means of sealing are a flexible flap.

7. A drag-head according to claim 5, wherein the means of sealing are a set of plates freely suspended to hinge behind the teeth, when seen in the direction of 10 trailing.

8. A drag-head according to any one of the preceding claims, wherein means of adjustment are provided for adjusting the position of the cutting teeth relative to the front edge of the housing. 15

9. A drag-head according to claim 8, wherein the elongate carrier is mounted so that it is free to swivel relative to the front edge of the housing.

10. A drag-head according to claim 9, whe re in the means of adjustment are 20 at least one piston cylinder assembly mounted between the front edge of the housing and the elongate carrier.

11. A drag-head according to claim 10, wherein the at least one piston cylinder assembly for positioning the cutting teeth is provided with a protection system for 25 limiting the pressure in the cylinder of the piston cylinder assembly.

12. A drag-head according to claim 11, wherein the protection system comprises an overpressure valve and buffer tank, which overpressure valve is coupled by its pressure side to the at least one piston cylinder assembly for 30 positioning the cutting teeth and its other side emerges in the buffer tank. 13

13. A drag-head according to any one of the preceding claims, wherein the housing is provided at the bottom, at its reinforced heel part, with a plough-shaped organ. 5

14. A drag-head according to any one of the preceding claims, wherein the housing is provided with a grid that extends essentially across a cross-section of the housing.

15. A hopper dredger comprising at least one suction pipe on which a drag 10 head according to any one of the preceding claims is mounted.

16. A hopper dredger according to claim 15, wherein a protection system is provided for limiting the axial loading of the suction pipe. 15

17. A hopper dredger according to claim 16, wherein the drag head is provided with means of adjustment for adjusting the position of the cutting teeth relative to the front edge of the housing; and wherein the elongate carrier is mounted so that it is free to swivel around a swivel axis relative to the front edge of the housing; the protective system being 20 adapted to use a measure of the moment of the elongate carrier around said swivel axis.

18. A hopper dredger comprising at least one suction pipe on which a drag head according to claim 12 is mounted, wherein a protection system is provided 25 for limiting the axial loading of the suction pipe, wherein the housing comprises a fixed housing part and a visor mounted so that it is free to swivel relative to that fixed housing part, wherein at least one piston cylinder assembly is mounted between the visor and the fixed housing part for positioning the visor relative to the fixed housing part, wherein the protection system comprises a sensor system for 30 detecting cylinder fluid in the buffer tank, and wherein the hopper dredger is provided with control means for the at least one piston cylinder assembly for positioning the visor, which sensor system is linked to the control means. 14

19. A hopper dredger according to any one of claims 15 to 17, wherein at least one suction pipe has its bottom end made with a thickened wall.

20. A hopper dredger according to any one of claims 15 to 19, provided with a 5 first winch with a hoisting cable for hoisting and lowering the suction pipe, wherein the bottom end of the suction pipe is provided with a guide pulley for the hoisting cable in order to halve the loading of that first winch.

21. A hopper dredger according to claim 20, wherein the end of the hoisting 10 cable led over the guide pulley is coupled to a second winch, wherein a swell compensator is placed between each winch and the guide pulley.

22. A drag-head for a suction dredging apparatus substantially as herein described with reference to any one of the embodiments of the invention illustrated 15 in the accompanying drawings and/or examples.

23. A hopper dredger with at least one suction pipe substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples. 20