695:. Both designs were near-identical except for differences in the approach used for pivoting the pads. Michell mathematically derived the pressure distribution where a span-wise line pivot was placed, allowing the load to act through the point of maximum fluid pressure. The Kingsbury patent lacked this mathematical approach, and the pad's pivot point was placed in the geometric centre of the bearing. Michell's patent (in Britain and Australia) was granted in 1905, while Kingsbury's first patent attempt was 1907. Kingsbury's U.S. patent was eventually granted in 1911 after he demonstrated that he had been working on the concept for many years. As stated by Sydney Walker, a long-time employee of Michell's, the granting of Kingsbury's patent was "a blow which Michell found hard to accept".
638:
619:
207:
329:
36:
649:) utilises a thin film of pressurized air to provide an exceedingly low friction load-bearing interface between surfaces. The two surfaces don't touch. Being non-contact, air bearings avoid the traditional bearing-related problems of friction, wear, particulates, and lubricant handling, and offer distinct advantages in precision positioning, such as lacking backlash and stiction, as well as in high-speed applications.
713:. Fluid pressure causes the pad to tilt slightly, creating a narrow constriction between the shoe and the other bearing surface. A wedge of pressurised fluid builds behind this constriction, separating the moving parts. The tilt of the pad adaptively changes with bearing load and speed. Various design details ensure continued replenishment of the oil to avoid overheating and pad damage.
507:
practice, when bearing surfaces are pressed together, the fluid outflow is constricted. This significantly increases the pressure of the fluid between the bearing faces. As fluid bearing faces can be comparatively larger than rolling surfaces, even small fluid pressure differences cause large restoring forces, maintaining the gap.
502:
of the fluid leading to dynamic friction that increases with speed, but static friction is typically negligible. Hydrostatic gas bearings are among the lowest friction bearings even at very high speeds. However, lower fluid viscosity also typically means fluid leaks faster from the bearing surfaces,
652:
The fluid film of the bearing is air that flows through the bearing itself to the bearing surface. The design of the air bearing is such that, although the air constantly escapes from the bearing gap, the pressure between the faces of the bearing is enough to support the working loads. This pressure
210:
A hydrostatic bearing has two surfaces, one of which has fluid forced through a restrictive orifice, so that it fills the space between the surfaces so that it keeps them apart. If the gap between the surfaces reduces then the outflow via the edges of the bearing is reduced and the pressure goes up,
258:
Hydrodynamic bearings rely on bearing motion to suck fluid into the bearing, and may have high friction and short life at speeds lower than design, or during starts and stops. An external pump or secondary bearing may be used for startup and shutdown to prevent damage to the hydrodynamic bearing. A
614:
separated by axial grooves. The usage of the bearing has three major advantages: (i) pumped water going through the bearing is conveniently used as a lubricant, which reduces pump operation cost; (ii) water flow takes away heat and fine particles through the bearing grooves; and (iii) the natural
789:
Until now tilting pad bearings play an essential role for rotating equipment like expanders, pumps, gas or steam turbines or compressors. Next to the traditional babbitt bearings which were used since the early 20th century modern manufacturers like Miba use other materials for example Bronze or
506:
When a roller or ball is heavily loaded, fluid bearings have clearances that change less under load (are "stiffer") than mechanical bearings. It might seem that bearing stiffness, as with maximum design load, would be a simple function of average fluid pressure and the bearing surface area. In
510:
However, in lightly loaded bearings, such as disk drives, the typical ball bearing stiffnesses are ~10^7 MN/m. Comparable fluid bearings have stiffness of ~10^6 MN/m. Because of this, some fluid bearings, particularly hydrostatic bearings, are deliberately designed to pre-load the bearing to
364:
The thin films can be thought to have pressure and viscous forces acting on them. Because there is a difference in velocity there will be a difference in the surface traction vectors. Because of mass conservation we can also assume an increase in pressure, making the body forces different.
668:
is a game based on an aerostatic bearing which suspends the puck and players' paddles to provide low friction and thus sustain high puck speeds. The bearing uses a flat plane with periodic orifices which deliver air just over ambient pressure. The puck and paddles rest on air.
754:
became dramatically smaller and lighter, significantly more efficient, and remarkably free from maintenance troubles. It was estimated that the Royal Navy saved coal to a value of ÂŁ500,000 in 1918 alone as a result of fitting
Michell's tilting-pad bearings.
182:
bearings rely on the high speed of the journal (the part of the shaft resting on the fluid) to pressurize the fluid in a wedge between the faces. Fluid bearings are frequently used in high load, high speed or high precision applications where ordinary
310:
The thickness of the film thus exceeds the combined roughness of the surfaces. The coefficient of friction is lower than with boundary-layer lubrication. Hydrodynamic lubrication prevents wear in moving parts, and metal to metal contact is prevented.
243:, the fluid is pumped in through an orifice or through a porous material. Such bearings should be equipped with the shaft position control system, which adjusts the fluid pressure and consumption according to the rotation speed and shaft load.
254:
Hydrostatic bearings rely on an external pump. The power required by that pump contributes to system energy loss, just as bearing friction otherwise would. Better seals can reduce leak rates and pumping power, but may increase friction.
867:
431:
Bearing characteristic number: Since viscosity, velocity, and load determine the characteristics of a hydrodynamic condition, a bearing characteristic number was developed based on the effects of these on film thickness.
602:. They use a gas as the working fluid, usually air, and require no external pressurisation system but need careful design to prevent wear during spin-up and spin-down when the bearing makes physical contact.
490:
Most fluid bearings require little or no maintenance, and have almost unlimited life. Conventional rolling-element bearings usually have shorter life and require regular maintenance. Pumped hydrostatic and
656:
Aerodynamic bearings can only be operated in high-speed applications, aerostatic bearings are required for load bearing at low speed. Both types require highly finished surfaces and precise manufacturing.
615:
resilience of rubber gives the bearing good properties for shock and vibration absorption and wear resistance. Water lubricated rubber bearings operate under the condition of mixed-lubrication.
556:
Many types of fluid bearings can catastrophically seize under shock situations or unexpected loss of supply pressure. Ball bearings deteriorate more gradually and provide acoustic symptoms.
535:
Fluid bearings can be made with a lower NRRO (non repeatable run out) than a ball or rolling element bearing. This can be critical in modern hard disk drive and ultra precision spindles.
782:
with a rotating mass of about 165 tonnes and water turbine pressure adding another 40 tonnes. The bearing has been in nearly continuous service since 1912, with no parts replaced. The
514:
Fluid bearings often inherently add significant damping. This helps attenuate resonances at the gyroscopic frequencies of journal bearings (sometimes called conical or rocking modes).
738:. By 1913, the great merits of the tilting-pad bearing had been recognised for marine applications. The first British ship to be fitted out with the bearing was the cross-channel
198:
The fluid bearing may have been invented by French civil engineer L. D. Girard, who in 1852 proposed a system of railway propulsion incorporating water-fed hydraulic bearings.
553:
Power consumption and stiffness or damping greatly vary with temperature, which complicates the design and operation of a fluid bearing in wide temperature range situations.
191:
motor fluid bearings are both quieter and cheaper than the ball bearings they replace. Applications are very versatile and may even be used in complex geometries such as
786:
reported it was still in service as of 2000. As of 2002, the manufacturer estimated the bearings at
Holtwood should have a maintenance-free life of about 1,300 years.
575:
Unlike greaseless mechanical bearings, fluid bearings cannot operate at the extremely low temperatures needed for some specialized scientific research applications.
899:
487:
may require many high-precision rollers with complicated shapes. Hydrostatic and many gas bearings do have the complication and expense of external pumps.
532:, which is a little more than the background noise of a quiet room. Drives based on rolling-element bearings are typically at least 4 dB noisier.
771:
378:
Pressure within the fluid mass is greatest at some point approaching minimum clearance and lowest at the point of maximum clearance (due to divergence)
325:
The scale of these films is on the order of micrometers. Their convergence creates pressures normal to the surfaces they contact, forcing them apart.
517:
It is very difficult to make a mechanical bearing which is atomically smooth and round; and mechanical bearings deform in high-speed operation due to
483:
with a similar load rating. The bearing can be as simple as two smooth surfaces with seals to keep in the working fluid. In contrast, a conventional
1027:
219:
between the moving bearing faces, typically sealed around or under the rotating shaft. The moving parts do not come into contact, so there is no
566:
Fluid leakage; keeping fluid in the bearing can be a challenge for liquid types, vacuum recovery and filtration can be needed in some situations.
734:
at Cohuna on the Murray River, Victoria, Australia, just two years after
Michell had published and patented his three-dimensional solution to
223:; the load force is supported solely by the pressure of the moving fluid. There are two principal ways of getting the fluid into the bearing:
735:
259:
secondary bearing may have high friction and short operating life, but good overall service life if bearing starts and stops are infrequent.
730:
It is likely the first tilting pad bearing in service was built in 1907 by George
Weymoth (Pty) Ltd (under A.G.M. Michell's guidance) for a
684:
Michell/Kingsbury fluid dynamic tilting-pad bearings were invented independently and almost simultaneously by both
British-born Australian,
314:
Hydrodynamic lubrication requires thin, converging fluid films. These fluids can be liquid or gas, so long as they exhibit viscosity. In
354:
Conceptually the bearings can be thought of as two major geometric classes: bearing-journal (anti-friction), and plane-slider (friction).
498:
Fluid bearings generally have very low friction—far better than mechanical bearings. One source of friction in a fluid bearing is the
361:
can be used to derive the governing principles for the fluids. Note that when gases are used, their derivation is much more involved.
250:, the bearing rotation sucks the fluid on to the inner surface of the bearing, forming a lubricating wedge under or around the shaft.
884:
Hydraulique appliquée. Nouveau système de locomotion sur les chemins de fer (Applied hydraulics. New locomotion system for railways)
307:
Hydrodynamic (full film) lubrication is obtained when two mating surfaces are completely separated by a cohesive film of lubricant.
759:
178:
bearings are externally pressurized fluid bearings, where the fluid is usually oil, water or air, and is pressurized by a pump.
572:
Fluid bearing "pads" often have to be used in pairs or triples to avoid the bearing tilting and losing the fluid from one side.
569:
Oil fluid bearings are impractical in environments where oil leakage can be destructive or where maintenance is not economical.
159:
than many other types of bearings. Thus, it is possible for some fluid bearings to have near-zero wear if operated correctly.
495:
bearing designs retain low friction down to zero speed and need not suffer start/stop wear, provided the pump does not fail.
187:
would have shortened life or caused high noise and vibration. They are also used increasingly to reduce cost. For example,
709:
on pivots. When the bearing is in operation, the rotating part of the bearing carries fresh oil in to the pad area through
559:
Like cage frequency vibration in a ball bearing, the half frequency whirl is a bearing instability that generates eccentric
100:
637:
524:
Fluid bearings are typically quieter and smoother (more consistent friction) than rolling-element bearings. For example,
72:
17:
1010:
847:
119:
79:
547:
Bearings must maintain pressure to prevent wear and hydrostatic types may be completely immobile when depressurised.
1037:
720:
to support turbines and generators weighing hundreds of tons. They are also used in very heavy machinery, such as
598:
are a type of fluid dynamic air bearing that were introduced in high speed turbine applications in the 1960s by
1076:
86:
57:
53:
1049:– Movies and photos of hundreds of working mechanical-systems models at Cornell University. Also includes an
933:"A new model of water-lubricated rubber bearings for vibration analysis of flexible multistage rotor systems"
716:
Michell/Kingsbury fluid bearings are used in a wider variety of heavy-duty rotating equipment, including in
1058:– A technical discussion introducing air bearings and their many applications at Specialty Components Inc.
68:
215:
Fluid bearings are noncontact bearings that use a thin layer of rapidly moving pressurized liquid or gas
1086:
618:
865:, "Hydrostatic nut and lead screw assembly, and method of forming said nut", issued 1994-12-29
975:
538:
Tilting pad bearings are used as radial bearings for supporting and locating shafts in compressors.
989:
484:
421:
Pressure acts in all directions, hence it tends to squeeze the oil out of the ends of the bearing
404:
Increase in relative velocity tends towards a decrease in eccentricity of journal bearing centers
46:
762:(see reference link), the first Michell/Kingsbury fluid bearing in the US was installed in the
471:, to some extent, gives an indication of whether there will be hydrodynamic lubrication or not
147:
between the bearing surfaces. Since there is no contact between the moving parts, there is no
970:
610:
Water-lubricated rubber bearings have long cylindrical metal shell that hosts multiple rubber
528:
manufactured with fluid bearings have noise ratings for bearings/motors on the order of 20–24
384:
Film thickness at the point of minimum clearance increases with the use of more viscous fluids
211:
forcing the surfaces apart again, giving excellent control of the gap and giving low friction.
1056:
521:. In contrast, fluid bearings self-correct for minor imperfections and slight deformations.
341:
322:, heads are supported by hydrodynamic lubrication in which the fluid film is the atmosphere.
837:
1081:
944:
480:
297:
136:
93:
390:
With a given load and fluid, the thickness of the film will increase as speed is increased
8:
916:
717:
372:
Fluid film at the point of minimum thickness decreases in thickness as the load increases
948:
779:
599:
843:
809:
767:
518:
358:
375:
Pressure within the fluid mass increases as the film thickness decreases due to load
952:
911:
731:
692:
492:
220:
148:
904:
Scientific and
Technical Journal of Information Technologies, Mechanics and Optics
863:
882:
747:
724:
685:
525:
319:
188:
27:
Type of bearings which use pressurized liquid or gas between the bearing surfaces
1050:
804:
721:
710:
1061:
1046:
1040:
956:
206:
1070:
799:
775:
611:
418:
Also increases pressure within the film mass to provide a counteracting force
139:
in which the load is supported by a thin layer of rapidly moving pressurized
932:
763:
751:
678:
595:
590:
315:
293:
184:
179:
393:
Fluid friction increases as the viscosity of the lubricant becomes greater
387:
With same load, the pressure increases as the viscosity of fluid increases
632:
175:
900:"Element design for an inkjet system of hydrostatic gas bearing control"
550:
Overall power consumption is typically higher compared to ball bearings.
665:
646:
560:
328:
653:
may be generated externally (aerostatic) or internally (aerodynamic).
739:
689:
499:
283:
192:
156:
381:
Viscosity increases as pressure increases (more resistance to shear)
35:
350:
Externally-pressurized: Film exists due to external pressurization.
303:
The surfaces between which the fluid films move must be convergent.
529:
503:
thus requiring increased power for pumps or friction from seals.
287:
790:
Copper-Chromium as well to improve the bearings' performance.
699:
672:
140:
216:
746:, but many naval vessels were similarly equipped during the
1028:
ASME History
Brochure about Kingsbury's Susquehanna Bearing
783:
750:. The practical results were spectacular – the troublesome
152:
641:
Air bearings on a drill spindle for printed circuit boards
450:
Viscosity Ă— velocity/unit load = a dimensionless number =
401:
Fluid velocity depends on velocity of the journal or rider
622:
Air bearings used to provide linear and rotational motion
479:
Fluid bearings can be relatively cheap compared to other
144:
897:
347:
Squeeze film: Film exists due to relative normal motion.
1053:
of classic texts on mechanical design and engineering.
340:
Self-acting: Film exists due to relative motion. e.g.
407:
This is accompanied by greater minimum film thickness
1047:
Kinematic Models for Design
Digital Library (KMODDL)
979:, London, 31 March 2011. Retrieved on 23 March 2013.
563:
which can lead to poor performance and reduced life.
1063:– A video demonstration of a spherical air bearing.
645:Unlike contact-roller bearings, an air bearing (or
605:
439:
Increase in viscosity increases min. film thickness
60:. Unsourced material may be challenged and removed.
774:, US) in 1912. The 2.25-tonne bearing supports a
436:Increase in velocity increases min. film thickness
151:, allowing fluid bearings to have lower friction,
839:Hydrostatic, Aerostatic and Hybrid Bearing Design
415:Increase in load decreases minimum film thickness
1068:
474:
162:They can be broadly classified into two types:
442:Increase in load decreases min. film thickness
424:Increase in pressure increases fluid viscosity
332:Miba Hydrodynamic Tilting Pad Journal Bearing
673:Michell/Kingsbury tilting-pad fluid bearings
369:Hydrodynamic lubrication – characteristics:
262:
982:
1032:A 91-page 10.6MB NASA technical handbook
969:Stachowiak, Gwidon; Batchelor, Andrew W.
915:
398:Hydrodynamic condition – Fluid velocity:
120:Learn how and when to remove this message
636:
617:
327:
205:
930:
842:. Butterworth-Heinemann. pp. 1–4.
14:
1069:
880:
831:
829:
827:
825:
579:
1036:, NASA-RP-1126 by B.J.Hamrock, 1984
874:
917:10.17586/2226-1494-2015-15-5-921-929
835:
58:adding citations to reliable sources
29:
931:Liu, Shibing; Yang, Bingen (2015).
822:
24:
971:"Engineering Tribology pp 135–136"
764:Holtwood Hydroelectric Power Plant
25:
1098:
1021:
990:"Features of Linear INA Bearings"
898:Il’ina T.E., Prodan N.V. (2015).
336:Three types of bearings include:
606:Water-lubricated rubber bearings
584:
541:
34:
1034:Lubrication of Machine Elements
626:
412:Hydrodynamic condition – load:
296:flow behavior of fluid between
45:needs additional citations for
1003:
963:
937:Journal of Sound and Vibration
924:
891:
856:
13:
1:
881:Girard, L. Dominique (1852).
815:
686:Anthony George Maldon Michell
462:bearing characteristic number
475:Characteristics of operation
318:and spinning device, like a
201:
7:
793:
660:
10:
1103:
676:
630:
588:
957:10.1016/j.jsv.2015.03.052
511:increase the stiffness.
278:has essential elements:
263:Hydrodynamic lubrication
836:Rowe, W. Brian (2012).
772:Lancaster, Pennsylvania
485:rolling-element bearing
1011:"Miba Thrust Bearings"
887:. Ecole Polytechnique.
642:
623:
342:spiral groove bearings
333:
276:fluid-film lubrication
248:fluid-dynamic bearings
212:
164:fluid dynamic bearings
1077:Bearings (mechanical)
976:Butterworth–Heinemann
640:
621:
331:
209:
168:hydrodynamic bearings
718:hydroelectric plants
677:For other uses, see
172:hydrostatic bearings
54:improve this article
949:2015JSV...349..230L
580:Some fluid bearings
18:Hydrostatic bearing
780:electric generator
736:Reynold's equation
643:
624:
600:Garrett AiResearch
359:Reynolds equations
334:
286:, which must be a
213:
1087:French inventions
810:Sommerfeld number
768:Susquehanna River
758:According to the
519:centripetal force
130:
129:
122:
104:
16:(Redirected from
1094:
1015:
1014:
1007:
1001:
1000:
998:
997:
986:
980:
967:
961:
960:
928:
922:
921:
919:
895:
889:
888:
878:
872:
871:
870:
866:
860:
854:
853:
833:
732:centrifugal pump
725:propeller shafts
698:The bearing has
693:Albert Kingsbury
526:hard disk drives
493:aerostatic (gas)
460:is known as the
274:, also known as
221:sliding friction
149:sliding friction
125:
118:
114:
111:
105:
103:
62:
38:
30:
21:
1102:
1101:
1097:
1096:
1095:
1093:
1092:
1091:
1067:
1066:
1024:
1019:
1018:
1009:
1008:
1004:
995:
993:
988:
987:
983:
968:
964:
929:
925:
896:
892:
879:
875:
868:
862:
861:
857:
850:
834:
823:
818:
796:
748:First World War
682:
675:
663:
635:
629:
608:
593:
587:
582:
544:
477:
430:
320:hard disk drive
265:
204:
189:hard disk drive
166:(also known as
126:
115:
109:
106:
69:"Fluid bearing"
63:
61:
51:
39:
28:
23:
22:
15:
12:
11:
5:
1100:
1090:
1089:
1084:
1079:
1065:
1064:
1059:
1054:
1051:e-book library
1044:
1030:
1023:
1022:External links
1020:
1017:
1016:
1002:
981:
962:
923:
910:(5): 921–929.
890:
873:
855:
849:978-0123972392
848:
820:
819:
817:
814:
813:
812:
807:
805:Kugel fountain
802:
795:
792:
674:
671:
662:
659:
631:Main article:
628:
625:
607:
604:
589:Main article:
586:
583:
581:
578:
577:
576:
573:
570:
567:
564:
557:
554:
551:
548:
543:
540:
476:
473:
455:
454:
444:
443:
440:
437:
428:
427:
426:
425:
422:
419:
416:
410:
409:
408:
405:
402:
396:
395:
394:
391:
388:
385:
382:
379:
376:
373:
352:
351:
348:
345:
305:
304:
301:
291:
264:
261:
252:
251:
244:
203:
200:
133:Fluid bearings
128:
127:
42:
40:
33:
26:
9:
6:
4:
3:
2:
1099:
1088:
1085:
1083:
1080:
1078:
1075:
1074:
1072:
1062:
1060:
1057:
1055:
1052:
1048:
1045:
1042:
1039:
1035:
1031:
1029:
1026:
1025:
1012:
1006:
991:
985:
978:
977:
972:
966:
958:
954:
950:
946:
942:
938:
934:
927:
918:
913:
909:
905:
901:
894:
886:
885:
877:
864:
859:
851:
845:
841:
840:
832:
830:
828:
826:
821:
811:
808:
806:
803:
801:
800:Plain bearing
798:
797:
791:
787:
785:
781:
777:
776:water turbine
773:
769:
765:
761:
756:
753:
749:
745:
741:
737:
733:
728:
726:
723:
719:
714:
712:
708:
704:
701:
696:
694:
691:
688:and American
687:
680:
670:
667:
658:
654:
650:
648:
639:
634:
620:
616:
613:
603:
601:
597:
596:Foil bearings
592:
585:Foil bearings
574:
571:
568:
565:
562:
558:
555:
552:
549:
546:
545:
542:Disadvantages
539:
536:
533:
531:
527:
522:
520:
515:
512:
508:
504:
501:
496:
494:
488:
486:
482:
472:
470:
467:The value of
465:
463:
459:
453:
449:
448:
447:
441:
438:
435:
434:
433:
423:
420:
417:
414:
413:
411:
406:
403:
400:
399:
397:
392:
389:
386:
383:
380:
377:
374:
371:
370:
368:
367:
366:
362:
360:
355:
349:
346:
343:
339:
338:
337:
330:
326:
323:
321:
317:
312:
308:
302:
299:
295:
292:
289:
285:
281:
280:
279:
277:
273:
269:
260:
256:
249:
245:
242:
238:
234:
230:
226:
225:
224:
222:
218:
208:
199:
196:
194:
190:
186:
185:ball bearings
181:
177:
173:
169:
165:
160:
158:
154:
150:
146:
142:
138:
134:
124:
121:
113:
110:November 2013
102:
99:
95:
92:
88:
85:
81:
78:
74:
71: –
70:
66:
65:Find sources:
59:
55:
49:
48:
43:This article
41:
37:
32:
31:
19:
1033:
1005:
994:. Retrieved
992:. 2022-05-09
984:
974:
965:
940:
936:
926:
907:
903:
893:
883:
876:
858:
838:
788:
757:
752:thrust block
743:
729:
715:
711:viscous drag
706:
702:
697:
683:
679:Thrust block
664:
655:
651:
644:
627:Air bearings
609:
594:
591:Foil bearing
537:
534:
523:
516:
513:
509:
505:
497:
489:
478:
468:
466:
461:
457:
456:
451:
445:
429:
363:
356:
353:
335:
324:
316:computer fan
313:
309:
306:
300:and journal.
294:Hydrodynamic
275:
271:
268:Hydrodynamic
267:
266:
257:
253:
247:
241:air bearings
240:
236:
232:
229:fluid static
228:
214:
197:
180:Hydrodynamic
171:
167:
163:
161:
132:
131:
116:
107:
97:
90:
83:
76:
64:
52:Please help
47:verification
44:
1082:Lubrication
943:: 230–258.
690:tribologist
633:air bearing
446:Therefore,
272:lubrication
233:hydrostatic
176:Hydrostatic
1071:Categories
996:2022-11-16
816:References
666:Air hockey
647:air caster
561:precession
193:leadscrews
80:newspapers
1038:dead link
740:steamboat
700:sectional
500:viscosity
284:lubricant
235:and many
202:Operation
157:vibration
1041:new link
794:See also
766:(on the
661:Examples
481:bearings
137:bearings
945:Bibcode
770:, near
298:bearing
288:viscous
94:scholar
869:
846:
722:marine
612:staves
290:fluid.
170:) and
141:liquid
96:
89:
82:
75:
67:
744:Paris
705:, or
703:shoes
270:(HD)
217:fluid
101:JSTOR
87:books
844:ISBN
784:ASME
778:and
760:ASME
742:the
707:pads
357:The
155:and
153:wear
135:are
73:news
953:doi
941:349
912:doi
246:In
239:or
237:gas
227:In
145:gas
143:or
56:by
1073::
973:,
951:.
939:.
935:.
908:15
906:.
902:.
824:^
727:.
530:dB
464:.
282:A
231:,
195:.
174:.
1043:.
1013:.
999:.
959:.
955::
947::
920:.
914::
852:.
681:.
469:C
458:C
452:C
344:.
123:)
117:(
112:)
108:(
98:·
91:·
84:·
77:·
50:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
