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Estimated reliability of the results of ultrasonic inspection of tubes
as a n a v e r a g e of the i n t e r f e r e n c e f i e l d of e l a s t i c w a v e s in a m e d i u m w i t h a l a r g e n u m b e r of i n h o m o g e n e i t i e s . A m p l i t u d e s c a t t e r i n g coefficients are obtained for spherical inclus i o n s a n d a r b i t r a r y c o m p o n e n t s of the m e d i u m , a s s u m i n g t h a t t h e d i m e n s i o n s of the s c a t t e r i n g c e n t r e s a n d t h e i r s p a c i n g a r e s m a l l in c o m p a r i s o n w i t h the w a v e l e n g t h . ( U l t r a s o n i c s 1969, a b s t r a c t 911)
NEWCOMB, C. P . , SHAW, R. W. U l t r a s o n i c a t t e n u a t i o n in s u p e r c o n d u c t i n g m e r c u r y and m e r c u r y - c a d m i u m s i n g l e c r y s t a l s . P h y s i c a l Review, Vol 173, No 2 ( S e p t e m b e r 1968) pp 5 0 9 - 5 1 5 A s y s t e m a t i c s t u d y is g i v e n of the d e v i a t i o n s of the r a t i o of e l e c t r o n i c a t t e n u a t i o n in the s u p e r c o n d u c t i n g s t a t e to t h a t in t h e n o r m a l s t a t e , (C~s/C~n), f o r l o n g i t u d i n a l u l t r a s o u n d f r o m t h a t p r e d i c t e d b y the BCS t h e o r y . T h e main points given are: 1 The d r o p in C~s/C~n w i t h d e c r e a s i n g t e m p e r a t u r e n e a r T c is g r e a t e r t h a n t h a t p r e d i c t e d by BCS. 2 T h e r a p i d i t y of the d r o p i n c r e a s e d w i t h i n c r e a s i n g f r e q u e n c y in a l l p u r e s a m p l e s , was frequency independent, and decreased w i t h d o p i n g c o n c e n t r a t i o n in d o p e d s a m ples. Mercury single crystals, polycrystals and mercury single crystals with concentrations of c a d m i u m i m p u r i t y r a n g i n g f r o m 0 . 0 1 to 0.10% were studied using a pulse echo techn i q u e at f r e q u e n c i e s f r o m 1 0 - 1 3 0 M H z , a n d low t e m p e r a t u r e s . T h e o b s e r v e d d e v i a t i o n s f r o m BCS t h e o r y c a n n o t be a d e q u a t e l y explained by dislocation attenuation or by m u l t i p l e a n i s o t r o p i c e n e r g y g a p s . (21 r e f e r e n c e s , 10 f i g u r e s ) ( U l t r a s o n i c s 1969, a b s t r a c t 912)
NIKOLAEVA, L. A., ROZINA, M. V., YABLONIK, L. M. E s t i m a t e d r e l i a b i l i t y of the r e s u l t s of u l t r a s o n i c i n s p e c t i o n of t u b e s . D e f e k t o s k o p i y a , No 1 (1968) pp 4 0 - 4 7 Taking as an example an automatic ultras o n i c m o n i t o r f o r t u b e s (by c o m p o u n d i n g the l a w of d i s t r i b u t i o n of d e f e c t s a s a f u n c t i o n of t h e i r d i m e n s i o n s a n d the a c c u r a c y of d e f e c t o s c o p e s ) , t h e a u t h o r s h a v e w o r k e d out the r e s u l t s to b e e x p e c t e d in t h e i n s p e c t i o n of t u b e s u n d e r d i f f e r e n t c o n d i t i o n s . T h e y a l s o i n d i c a t e w a y s of i m p r o v i n g the r e l i a b i l i t y of r e s u l t s . ( U l t r a s o n i c s 1969, a b s t r a c t 913)
NOBLE, F.W. D u a l frequency u l t r a s o n i c fluid f l o w m e t e r . T h e R e v i e w of S c i e n t i f i c I n s t r u m e n t s , Vol 39, No 9 ( S e p t e m b e r 1968) T h i s p a p e r g i v e s a d e t a i l e d a c c o u n t of the experimental technique used. Ultrasonic transit time or phase delay flowmeters m e a s u r e t h e d i f f e r e n c e b e t w e e n the t i m e f o r an a c o u s t i c w a v e to t r a v e l a f i x e d d i s t a n c e u p s t r e a m a n d t h a t d o w n s t r e a m . The mechanical or electronic transposition s w i t c h e s i n t r o d u c e n o i s e a n d l i m i t the f r e quency response. The system described e l i m i n a t e s t h e n e e d f o r t r a n s p o s i t i o n b y the u s e of two d i f f e r e n t f r e q u e n c i e s p r o p a g a t e d c o n t i n u o u s l y in o p p o s i t e d i r e c t i o n s . T i m e r e s o l u t i o n s of the o r d e r of 1 0 - 1 ° s a n d f r e q u e n c y r e s p o n s e in the kHz r a n g e a r e s t a t e d to b e r e a d i l y a t t a i n e d . ( U l t r a s o n i c s 1969, a b s t r a c t 914)
N O Z D R E V , V. F., S T E P A N O V , N.G. Intersection of the ultrasonic velocity c u r v e s for a liquid and s a t u r a t e d v a p o r s n e a r t h e c r i t i c a l p o i n t . Soviet P h y s i c s A c o u s t i c s , Vol 13, No 4 ( A p r i l - J u n e 1968) pp 5 3 8 - 5 3 9 A t f r e q u e n c i e s b e t w e e n 3 a n d 4MHz, it w a s s h o w n t h a t the v e l o c i t y of s o u n d in the s a t u r a t e d v a p o u r s of d i m e t h y l d i c h l o r o s i l a n e a n d 82
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of t r i m e t b y l c h l o r o s i l a n e e x c e e d e d the v e l o c i t y in the l i q u i d p h a s e by 2.8°/° a n d 3.5°/° r e s p e c t i v e l y . T h e s e r e s u l t s c o n f i r m e d the S c h n e i d e r effect, w h i c h h a d b e e n o b s e r v e d in s u l p h u r h e x a f l u o r i d e , t h a t t h e r e is a r e g i o n j u s t b e l o w the c r i t i c a l t e m p e r a t u r e w h e r e the v e l o c i t y of s o u n d is g r e a t e r in the s a t u r a t e d v a p o u r t h a n in the liquid. Since i d e n t i c a l m e a s u r e m e n t s did not s h o w the S c h n e i d e r e f f e c t in m e t h y l t r i c h l o r o s i l a n e o r e t h y l t r i c h l o r o s i l a n e , it d e p e n d s on the s t r u c t u r e of the s u b s t a n c e . (5 R e f e r e n c e s , 1 F i g u r e , 1 Table) ( U l t r a s o n i c s 1969, a b s t r a c t 915)
O S T R O F S K Y , B., PARRISH, C. B. U l t r a s o n i c i n s p e c t i o n of b o i l e r t u b e s . M a t e r i a l s E v a l u a t i o n , Vol 26, No 6 (June 1968) pp 106-108, 119 In a n i m m e r s i o n u l t r a s o n i c d e t e c t o r of the e r o s i o n a n d c o r r o s i o n p a t t e r n s in b o i l e r tubes, a focused transducer (0.79cm diameter, 20MHz f r e q u e n c y ) is m o u n t e d on a s i x - w h e e l ed, s p r i n g - l o a d e d c a r r i a g e s o t h a t it c a n be moved linearly and rotated. The pulse-echo t e c h n i q u e (with t r a n s d u c e r s e p a r a t e d f r o m the w a l l of the tube by 0 . 0 1 3 - 0 . 0 2 8 c m of c o u p l a n t ) o r the r e s o n a n c e t e c h n i q u e (with s p e c i a l p r o b e s to c o n t a c t the tubes) w e r e used. This detector was generally successful but w a s u n a b l e to o b t a i n r e a d i n g s on the s i d e w a i l s of b e n d s ( t h r o u g h m i s a l i g n m e n t ) a n d w a s not s u i t e d to d e t e c t i n g l o c a l i z e d p i t t e d a r e a s ( t h r o u g h t i m e r e q u i r e d ) . (4 R e f e r e n c e s , 5 F i g u r e s ) ( U l t r a s o n i c s 1969, a b s t r a c t 916) P A P A D A K I S , E. P . U l t r a s o n i c attenuation in thin s p e c i m e n s driven t h r o u g h b u f f e r r o d s . J o u r n a l of the A c o u s t i c a l Society of A m e r i c a , Vol 44, No 3, ( S e p t e m b e r 1968) pp 7 2 4 - 7 3 4 Brass samples and a transducer are bonded at e i t h e r e n d of a b u f f e r r o d . The t r a n s d u c e r is e x c i t e d by r f p u l s e s t h r e e t i m e s l o n g e r t h a n the e l a s t i c w a v e t r a v e l t i m e in the s p e c i m e n but s h o r t e r t h a n t h a t in the b u f f e r . T h e f a c e s of the s p e c i m e n (one in c o n t a c t with the buffer) a c t a s a m u l t i p l e - p a t h i n t e r f e r o m e t e r a n d the r e t u r n i n g e c h o is s t e p m o d u l a t e d a t each reflection. Expressions are derived for the r e f l e c t i o n c o e f f i c i e n t at the b u f f e r - s p e c i m e n i n t e r f e r e n c e a n d the a t t e n u a t i o n in the s p e c i m e n . R e s u l t s a r e i n t e r p r e t e d at d i f f e r e n t f r e q u e n c i e s , g i v i n g the v a r i a t i o n of a t t e n u a t i o n w i t h f r e q u e n c y . An a p p e n d i x c o n s i d e r s m e a s u r e m e n t e r r o r s . ( U l t r a s o n i c s 1969, a b s t r a c t 917)
P A R K I N S O N , M. J. M e a s u r e m e n t of the m a s s flow rate of airborne powdered material in a duct. Journal of Scientific Instruments, Series 2, Vol 1 (August 1968) pp 823,824 The absolute mass flow rate for airborne pulverized coal is obtained from measurement of the gas velocity, using an ultrasonic meter, and the density of the coal/air mixture, using a ~-absorption gauge. The method may be extended to a range of solid/gas mixtures. A n ultrasonic receiver (a magnetostrictive transducer, hermetically sealed and operated a t 40kHz) u p s t r e a m f r o m a t r a n s m i t t e r r e c o r d s a s i g n a l l a t e r t h a n it w o u l d in s t a tionary air; a similar receiver downstream r e c o r d s the p u l s e s o o n e r . T h e t i m e i n t e r v a l b e t w e e n t h e s e r e c o r d s m e a s u r e s the m e a n v e l o c i t y of a i r - - c l o s e e n o u g h to the v e l o c i t y of the p o w d e r e d m a t e r i a l . (6 R e f e r e n c e s , 2 F i g u r e s ) ( U l t r a s o n i c s 1969, a b s t r a c t 918) P E V E R L E Y , J. R. Magnetoacoustic effect in potassium. Physical Review, Vol 173, No 3 (September 1968) pp 6 8 9 - 6 9 1 T h e i n c r e a s e d a t t e n u a t i o n of s o u n d w a v e s in h i g h m a g n e t i c f i e l d s , by c o m p a r i s o n with f r e e - e l e c t r o n t h e o r y , i s not s o s p e c t a c u l a r a s s o m e of the m a g n e t o r e s i s t a n c e e f f e c t s . L o n g i t u d i n a l s o u n d w a v e s of f r e q u e n c i e s 60, 100 a n d 140MHz w e r e p r o p a g a t e d in the [110]
d i r e c t i o n in a s i n g l e p o t a s s i u m c r y s t a l . T h e a t t e n u a t i o n w a s m e a s u r e d a s a f u n c t i o n of the t r a n s v e r s e m a g n e t i c field, a n d f i t t e d with the f r e e - e l e c t r o n t h e o r y u s i n g the m e a n f r e e p a t h of the e l e c t r o n s a s a p a r a m e t e r to be d e t e r m i n e d . The a n o m a l o u s l y l a r g e a t t e n u a t i o n m e a s u r e d at high f i e l d s s u g g e s t s t h a t h i g h - f i e l d u l t r a s o n i c a t t e n u a t i o n a n d the m a g netoresistance behaviour have a common c a u s e . (14 R e f e r e n c e s , 1 f i g u r e ) ( U l t r a s o n i c s 1969, a b s t r a c t 919)
P O L L O C K , A. A. A computer program to generate longitudinal frequency response functions. Acustica, Vol 19, No 5 (1967/68) pp 292-294 A computer p r o g r a m m e models the pulse transmission process of a thin dumb-bell shaped specimen for the following cases: (1) with no transducer loading, two families of modes are excited: single peaks at odd multiples of 33kHz and double peaks on either side of even multiples of 33kHz; (2) and (3) show the untidy responses of the specimen and a carelessly-matched transducer load; (4) shows the resonant response of a transducer at 267kHz when its impedance match with the specimen is perfect. M o r e complicated systems may be modelled in this way. (2 Figures) Ultransonics 1969, abstract 920)
P O L O T S K I I , I. G., P R O K O P E N K O , G. 1. U l t r a s o n i c damping in s t r a i n e d m o l y b d e num and niobium single crystals in different crystallographic directions. Soviet Physics--Acoustics, Vol 14, No i (JulySeptember 1968) pp 107-109 Single crystals of molybdenum and niobium are used to study the influence of orientation on the relaxation damping peaks in strained metals. Temperature dependence at frequencies of 5, 10 and 30 M H z in such prestrained single crystals are investigated. Crystal orientation is determined by the use of inverted Laue x-ray photography. Samples are strained 10 per cent in the crystallographic directions [100], [110] and [111]. A n ultrasonic pulse apparatus is used to determine the sound absorption. Results show the existence of a damping peak. Peak displacement with temperature variation is shown to be greater in molybdenum than in niobium. Activation energies for the relaxation peaks are compared. (Ultrasonics 1969, abstract 921)
PRIDIE, R . B., T U R N B U L L , T . A . D i a g n o s i s of p e r i c a r d i a l e f f u s i o n b y u l t r a s o u n d . B r i t i s h M e d i c a l J o u r n a l , Vol 3 (1968) pp 3 4 1 , 3 5 6 - 3 5 7 B e t w e e n the p o s t e r i o r p a r t of the a n t e r i o r c h e s t w a l l a n d the a n t e r i o r s u r f a c e of the anterior myocardinm and pericardium, there is a b a r e a r e a w h i c h v a r i e s w i t h t h e s a m e p e r i o d i c i t y a s the c a r d i a c c y c l e - - s o t h a t t h i s b a r e a r e a m a y be m o n i t o r e d by u l t r a s o u n d to d i a g n o s e p e r i c a r d i a ] e f f u s i o n . T h e i n s t r u m e n t u s e d is the E s k o l i n e 20 u l t r a s o n o s c o p e m a c h i n e w h i c h u s e s a f r e q u e n c y of 2 . 2 5 M H z with p u l s e s of l p s a n d a p u l s e r e p e t i t i o n r a t e of 1 0 0 0 / s . Since d i a g n o s i s i s e f f e c t e d s i m p l y by p l a c i n g f l a t t r a n s d u c e r on the p a t i e n t ' s c h e s t , t h i s m e t h o d is a t r a u m a t i c . (10 R e f e r e n c e s , 5 F i g u r e s ) ( U l t r a s o n i c s 1969, a b s t r a c t 922)
RASHID, A. A p o s s i b i l i t y of generating m i c r o w a v e acoustic w a v e s in f e r r o m a g n e t i c c r y s t a l s . I n s t i t u t e of E l e c t r i c a l a n d E l e c t r o n i c s E n g i n e e r s T r a n s a c t i o n s on S o n i c s a n d U l t r a s o n i c s , Vol SU-15, No 4 ( O c t o b e r 1968) pp 229±230 T h e i n t e r a c t i o n of s p i n w a v e a n d a c o u s t i c w a v e in a f e r r o m a g n e t i c c r y s t a l i s d e s c r i b e d . It is s h o w n t h a t the a t t e n u a t i o n is m u c h h i g h e r f o r the r i g h t s e n s e p o l a r l s a t i o n t h a n f o r the left s e n s e of p o l a r i s a t i o n . H e n c e left
NEWCOMB, C. P . , SHAW, R. W. U l t r a s o n i c a t t e n u a t i o n in s u p e r c o n d u c t i n g m e r c u r y and m e r c u r y - c a d m i u m s i n g l e c r y s t a l s . P h y s i c a l Review, Vol 173, No 2 ( S e p t e m b e r 1968) pp 5 0 9 - 5 1 5 A s y s t e m a t i c s t u d y is g i v e n of the d e v i a t i o n s of the r a t i o of e l e c t r o n i c a t t e n u a t i o n in the s u p e r c o n d u c t i n g s t a t e to t h a t in t h e n o r m a l s t a t e , (C~s/C~n), f o r l o n g i t u d i n a l u l t r a s o u n d f r o m t h a t p r e d i c t e d b y the BCS t h e o r y . T h e main points given are: 1 The d r o p in C~s/C~n w i t h d e c r e a s i n g t e m p e r a t u r e n e a r T c is g r e a t e r t h a n t h a t p r e d i c t e d by BCS. 2 T h e r a p i d i t y of the d r o p i n c r e a s e d w i t h i n c r e a s i n g f r e q u e n c y in a l l p u r e s a m p l e s , was frequency independent, and decreased w i t h d o p i n g c o n c e n t r a t i o n in d o p e d s a m ples. Mercury single crystals, polycrystals and mercury single crystals with concentrations of c a d m i u m i m p u r i t y r a n g i n g f r o m 0 . 0 1 to 0.10% were studied using a pulse echo techn i q u e at f r e q u e n c i e s f r o m 1 0 - 1 3 0 M H z , a n d low t e m p e r a t u r e s . T h e o b s e r v e d d e v i a t i o n s f r o m BCS t h e o r y c a n n o t be a d e q u a t e l y explained by dislocation attenuation or by m u l t i p l e a n i s o t r o p i c e n e r g y g a p s . (21 r e f e r e n c e s , 10 f i g u r e s ) ( U l t r a s o n i c s 1969, a b s t r a c t 912)
NIKOLAEVA, L. A., ROZINA, M. V., YABLONIK, L. M. E s t i m a t e d r e l i a b i l i t y of the r e s u l t s of u l t r a s o n i c i n s p e c t i o n of t u b e s . D e f e k t o s k o p i y a , No 1 (1968) pp 4 0 - 4 7 Taking as an example an automatic ultras o n i c m o n i t o r f o r t u b e s (by c o m p o u n d i n g the l a w of d i s t r i b u t i o n of d e f e c t s a s a f u n c t i o n of t h e i r d i m e n s i o n s a n d the a c c u r a c y of d e f e c t o s c o p e s ) , t h e a u t h o r s h a v e w o r k e d out the r e s u l t s to b e e x p e c t e d in t h e i n s p e c t i o n of t u b e s u n d e r d i f f e r e n t c o n d i t i o n s . T h e y a l s o i n d i c a t e w a y s of i m p r o v i n g the r e l i a b i l i t y of r e s u l t s . ( U l t r a s o n i c s 1969, a b s t r a c t 913)
NOBLE, F.W. D u a l frequency u l t r a s o n i c fluid f l o w m e t e r . T h e R e v i e w of S c i e n t i f i c I n s t r u m e n t s , Vol 39, No 9 ( S e p t e m b e r 1968) T h i s p a p e r g i v e s a d e t a i l e d a c c o u n t of the experimental technique used. Ultrasonic transit time or phase delay flowmeters m e a s u r e t h e d i f f e r e n c e b e t w e e n the t i m e f o r an a c o u s t i c w a v e to t r a v e l a f i x e d d i s t a n c e u p s t r e a m a n d t h a t d o w n s t r e a m . The mechanical or electronic transposition s w i t c h e s i n t r o d u c e n o i s e a n d l i m i t the f r e quency response. The system described e l i m i n a t e s t h e n e e d f o r t r a n s p o s i t i o n b y the u s e of two d i f f e r e n t f r e q u e n c i e s p r o p a g a t e d c o n t i n u o u s l y in o p p o s i t e d i r e c t i o n s . T i m e r e s o l u t i o n s of the o r d e r of 1 0 - 1 ° s a n d f r e q u e n c y r e s p o n s e in the kHz r a n g e a r e s t a t e d to b e r e a d i l y a t t a i n e d . ( U l t r a s o n i c s 1969, a b s t r a c t 914)
N O Z D R E V , V. F., S T E P A N O V , N.G. Intersection of the ultrasonic velocity c u r v e s for a liquid and s a t u r a t e d v a p o r s n e a r t h e c r i t i c a l p o i n t . Soviet P h y s i c s A c o u s t i c s , Vol 13, No 4 ( A p r i l - J u n e 1968) pp 5 3 8 - 5 3 9 A t f r e q u e n c i e s b e t w e e n 3 a n d 4MHz, it w a s s h o w n t h a t the v e l o c i t y of s o u n d in the s a t u r a t e d v a p o u r s of d i m e t h y l d i c h l o r o s i l a n e a n d 82
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of t r i m e t b y l c h l o r o s i l a n e e x c e e d e d the v e l o c i t y in the l i q u i d p h a s e by 2.8°/° a n d 3.5°/° r e s p e c t i v e l y . T h e s e r e s u l t s c o n f i r m e d the S c h n e i d e r effect, w h i c h h a d b e e n o b s e r v e d in s u l p h u r h e x a f l u o r i d e , t h a t t h e r e is a r e g i o n j u s t b e l o w the c r i t i c a l t e m p e r a t u r e w h e r e the v e l o c i t y of s o u n d is g r e a t e r in the s a t u r a t e d v a p o u r t h a n in the liquid. Since i d e n t i c a l m e a s u r e m e n t s did not s h o w the S c h n e i d e r e f f e c t in m e t h y l t r i c h l o r o s i l a n e o r e t h y l t r i c h l o r o s i l a n e , it d e p e n d s on the s t r u c t u r e of the s u b s t a n c e . (5 R e f e r e n c e s , 1 F i g u r e , 1 Table) ( U l t r a s o n i c s 1969, a b s t r a c t 915)
O S T R O F S K Y , B., PARRISH, C. B. U l t r a s o n i c i n s p e c t i o n of b o i l e r t u b e s . M a t e r i a l s E v a l u a t i o n , Vol 26, No 6 (June 1968) pp 106-108, 119 In a n i m m e r s i o n u l t r a s o n i c d e t e c t o r of the e r o s i o n a n d c o r r o s i o n p a t t e r n s in b o i l e r tubes, a focused transducer (0.79cm diameter, 20MHz f r e q u e n c y ) is m o u n t e d on a s i x - w h e e l ed, s p r i n g - l o a d e d c a r r i a g e s o t h a t it c a n be moved linearly and rotated. The pulse-echo t e c h n i q u e (with t r a n s d u c e r s e p a r a t e d f r o m the w a l l of the tube by 0 . 0 1 3 - 0 . 0 2 8 c m of c o u p l a n t ) o r the r e s o n a n c e t e c h n i q u e (with s p e c i a l p r o b e s to c o n t a c t the tubes) w e r e used. This detector was generally successful but w a s u n a b l e to o b t a i n r e a d i n g s on the s i d e w a i l s of b e n d s ( t h r o u g h m i s a l i g n m e n t ) a n d w a s not s u i t e d to d e t e c t i n g l o c a l i z e d p i t t e d a r e a s ( t h r o u g h t i m e r e q u i r e d ) . (4 R e f e r e n c e s , 5 F i g u r e s ) ( U l t r a s o n i c s 1969, a b s t r a c t 916) P A P A D A K I S , E. P . U l t r a s o n i c attenuation in thin s p e c i m e n s driven t h r o u g h b u f f e r r o d s . J o u r n a l of the A c o u s t i c a l Society of A m e r i c a , Vol 44, No 3, ( S e p t e m b e r 1968) pp 7 2 4 - 7 3 4 Brass samples and a transducer are bonded at e i t h e r e n d of a b u f f e r r o d . The t r a n s d u c e r is e x c i t e d by r f p u l s e s t h r e e t i m e s l o n g e r t h a n the e l a s t i c w a v e t r a v e l t i m e in the s p e c i m e n but s h o r t e r t h a n t h a t in the b u f f e r . T h e f a c e s of the s p e c i m e n (one in c o n t a c t with the buffer) a c t a s a m u l t i p l e - p a t h i n t e r f e r o m e t e r a n d the r e t u r n i n g e c h o is s t e p m o d u l a t e d a t each reflection. Expressions are derived for the r e f l e c t i o n c o e f f i c i e n t at the b u f f e r - s p e c i m e n i n t e r f e r e n c e a n d the a t t e n u a t i o n in the s p e c i m e n . R e s u l t s a r e i n t e r p r e t e d at d i f f e r e n t f r e q u e n c i e s , g i v i n g the v a r i a t i o n of a t t e n u a t i o n w i t h f r e q u e n c y . An a p p e n d i x c o n s i d e r s m e a s u r e m e n t e r r o r s . ( U l t r a s o n i c s 1969, a b s t r a c t 917)
P A R K I N S O N , M. J. M e a s u r e m e n t of the m a s s flow rate of airborne powdered material in a duct. Journal of Scientific Instruments, Series 2, Vol 1 (August 1968) pp 823,824 The absolute mass flow rate for airborne pulverized coal is obtained from measurement of the gas velocity, using an ultrasonic meter, and the density of the coal/air mixture, using a ~-absorption gauge. The method may be extended to a range of solid/gas mixtures. A n ultrasonic receiver (a magnetostrictive transducer, hermetically sealed and operated a t 40kHz) u p s t r e a m f r o m a t r a n s m i t t e r r e c o r d s a s i g n a l l a t e r t h a n it w o u l d in s t a tionary air; a similar receiver downstream r e c o r d s the p u l s e s o o n e r . T h e t i m e i n t e r v a l b e t w e e n t h e s e r e c o r d s m e a s u r e s the m e a n v e l o c i t y of a i r - - c l o s e e n o u g h to the v e l o c i t y of the p o w d e r e d m a t e r i a l . (6 R e f e r e n c e s , 2 F i g u r e s ) ( U l t r a s o n i c s 1969, a b s t r a c t 918) P E V E R L E Y , J. R. Magnetoacoustic effect in potassium. Physical Review, Vol 173, No 3 (September 1968) pp 6 8 9 - 6 9 1 T h e i n c r e a s e d a t t e n u a t i o n of s o u n d w a v e s in h i g h m a g n e t i c f i e l d s , by c o m p a r i s o n with f r e e - e l e c t r o n t h e o r y , i s not s o s p e c t a c u l a r a s s o m e of the m a g n e t o r e s i s t a n c e e f f e c t s . L o n g i t u d i n a l s o u n d w a v e s of f r e q u e n c i e s 60, 100 a n d 140MHz w e r e p r o p a g a t e d in the [110]
d i r e c t i o n in a s i n g l e p o t a s s i u m c r y s t a l . T h e a t t e n u a t i o n w a s m e a s u r e d a s a f u n c t i o n of the t r a n s v e r s e m a g n e t i c field, a n d f i t t e d with the f r e e - e l e c t r o n t h e o r y u s i n g the m e a n f r e e p a t h of the e l e c t r o n s a s a p a r a m e t e r to be d e t e r m i n e d . The a n o m a l o u s l y l a r g e a t t e n u a t i o n m e a s u r e d at high f i e l d s s u g g e s t s t h a t h i g h - f i e l d u l t r a s o n i c a t t e n u a t i o n a n d the m a g netoresistance behaviour have a common c a u s e . (14 R e f e r e n c e s , 1 f i g u r e ) ( U l t r a s o n i c s 1969, a b s t r a c t 919)
P O L L O C K , A. A. A computer program to generate longitudinal frequency response functions. Acustica, Vol 19, No 5 (1967/68) pp 292-294 A computer p r o g r a m m e models the pulse transmission process of a thin dumb-bell shaped specimen for the following cases: (1) with no transducer loading, two families of modes are excited: single peaks at odd multiples of 33kHz and double peaks on either side of even multiples of 33kHz; (2) and (3) show the untidy responses of the specimen and a carelessly-matched transducer load; (4) shows the resonant response of a transducer at 267kHz when its impedance match with the specimen is perfect. M o r e complicated systems may be modelled in this way. (2 Figures) Ultransonics 1969, abstract 920)
P O L O T S K I I , I. G., P R O K O P E N K O , G. 1. U l t r a s o n i c damping in s t r a i n e d m o l y b d e num and niobium single crystals in different crystallographic directions. Soviet Physics--Acoustics, Vol 14, No i (JulySeptember 1968) pp 107-109 Single crystals of molybdenum and niobium are used to study the influence of orientation on the relaxation damping peaks in strained metals. Temperature dependence at frequencies of 5, 10 and 30 M H z in such prestrained single crystals are investigated. Crystal orientation is determined by the use of inverted Laue x-ray photography. Samples are strained 10 per cent in the crystallographic directions [100], [110] and [111]. A n ultrasonic pulse apparatus is used to determine the sound absorption. Results show the existence of a damping peak. Peak displacement with temperature variation is shown to be greater in molybdenum than in niobium. Activation energies for the relaxation peaks are compared. (Ultrasonics 1969, abstract 921)
PRIDIE, R . B., T U R N B U L L , T . A . D i a g n o s i s of p e r i c a r d i a l e f f u s i o n b y u l t r a s o u n d . B r i t i s h M e d i c a l J o u r n a l , Vol 3 (1968) pp 3 4 1 , 3 5 6 - 3 5 7 B e t w e e n the p o s t e r i o r p a r t of the a n t e r i o r c h e s t w a l l a n d the a n t e r i o r s u r f a c e of the anterior myocardinm and pericardium, there is a b a r e a r e a w h i c h v a r i e s w i t h t h e s a m e p e r i o d i c i t y a s the c a r d i a c c y c l e - - s o t h a t t h i s b a r e a r e a m a y be m o n i t o r e d by u l t r a s o u n d to d i a g n o s e p e r i c a r d i a ] e f f u s i o n . T h e i n s t r u m e n t u s e d is the E s k o l i n e 20 u l t r a s o n o s c o p e m a c h i n e w h i c h u s e s a f r e q u e n c y of 2 . 2 5 M H z with p u l s e s of l p s a n d a p u l s e r e p e t i t i o n r a t e of 1 0 0 0 / s . Since d i a g n o s i s i s e f f e c t e d s i m p l y by p l a c i n g f l a t t r a n s d u c e r on the p a t i e n t ' s c h e s t , t h i s m e t h o d is a t r a u m a t i c . (10 R e f e r e n c e s , 5 F i g u r e s ) ( U l t r a s o n i c s 1969, a b s t r a c t 922)
RASHID, A. A p o s s i b i l i t y of generating m i c r o w a v e acoustic w a v e s in f e r r o m a g n e t i c c r y s t a l s . I n s t i t u t e of E l e c t r i c a l a n d E l e c t r o n i c s E n g i n e e r s T r a n s a c t i o n s on S o n i c s a n d U l t r a s o n i c s , Vol SU-15, No 4 ( O c t o b e r 1968) pp 229±230 T h e i n t e r a c t i o n of s p i n w a v e a n d a c o u s t i c w a v e in a f e r r o m a g n e t i c c r y s t a l i s d e s c r i b e d . It is s h o w n t h a t the a t t e n u a t i o n is m u c h h i g h e r f o r the r i g h t s e n s e p o l a r l s a t i o n t h a n f o r the left s e n s e of p o l a r i s a t i o n . H e n c e left