in of , 50061, 4 999; in 999; 000is of a is by In of of to on of an on of of a as on in of # 2000 td .A. B. of in is to a to be as to of a 1,2. of to is of of an of a of on to as to of in on 35. It is to of is to a to 8 of be to As of of a A a a a 0/$ 2000 td .0)000246 (2000) 825830* +86+D. of of of is of o/Ni of to of of to of on in by .5 mm)as iC .8 to by a 6 in to a in 6001800C. o i to to of is a is a of a of of of is of 00 in a 0G a a . a , 10, 4 A,is an by be or no In in a of an 5 is by of on In a 50 W 625 0 N 0, 120,404C a .5 mm/of m/s.A 0 3 4 16 of to a 10 at a .5 mm/by on a 0of by 3. of o/Ni 1(a) EM of of o/Ni a of of be of on be o/Ni by or of is of is at o/Ni )0% 6 (2000) 825830o i, of 1(b) of It be DM to o iC of by to 2 is a of It is a a is mm in of of an of as be of 3 of o/It by is by In 1, a is no on EM of o/Ni is 4. It be 1. of o/Ni 2. EM of o/Ni 3. of o/6 (2000) 825830 827by On of of of on of o/Ni of . It be of to of as be 1. of as 2.A of DM be of a of no of o/Ni of of is 5. of A in , it is of 0%of a on of a A an 16 a 0 A, 65 5 A in in 19 As to a to of of in is of on of o/a (=55 V, 14 (A) 4C 0=6 m/s 4. of o/Ni 5. of of o/Ni of )4 1910 655 16828 6 (2000) 825830is to of of is to of of on as on in of of is 6. It is of in SM of 7. m/s an 46 a be of o/Ni . o/Ni a as in of of of An in in 6. of of o/Ni of 0 81120 08240 28of 467. of of o/Ni 6 (2000) 825830 829 S. M. P. , 1998.2 1997.3 E. in of 7 (2) (1998) 669693.4 L T. of 7 (1996) 207220.5 H. of of 8 (2) (1989) 699708.6 E. of (1)