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Flight-tone and wing-stroke frequency of insects and the dynamics of insect flight
~ACUUM Classified Abstracts
I
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General Science a n d Engineering. C~td.
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I
chamber increased initially due to the dissociation of the oxygen b u t after a short while decreased again indicating t h a t the speed of diffusion of the oxygen from t h e interior of the body of the metal was slow. I t appears advisable therefore to reduce metal before it is sintered. Normal protective atmospheres are of little use in these operations as their partial oxygen pressure is comparatively high. The sintering of ceramics in a high vacuum is not necessarily an advantage. During the sintering process a partial reduction of the oxygen compound m a y take place and the finished product m a y no longer be of the required composition. Sommaire: Yes causes et le mdcanisme des changements chimiques, ~ l'int~rieur de compos~s d'oxydes m6talliques, lors de l'6vaporation sont ~tudi6s. Important Steps in Investment Casting United Kingdom. A brief description is given of the main exhibit of the Design and Research Centre a t the British Industries Fair, 1952. The subject was investment casting. Each step in the process of manufacturing jewellery b y this method was illustrated b y an exl~ibit of the production apparatus required. Nine steps were shown : (1) Making the Master Model, (2) Making the R u b b e r Moulds, (3) W a x Injector, (4) Mounting the W a x Pattern, (5) Selecting a Suitable Investment, (6) Investing, (7) Burning Out, (8) Casting and (9) Knocking out. Under (6) reference was made to the p a r t v a c u u m plays in the process. Sommaire : Br~ve note concernant l'ordre des opdrations dans la m6thode de moulage ~ la cite perdue. A Powder Camera Modification for High Temperature P h o t o g r a p h s United Kingdom. The design of a unit is described which facilitates th~ taking of high temperature powder photographs of steel specimens in the form of thin strips with the help of a n ordinary camera. I t consists of a 9 cm. diameter brass disc with a current lead a t the centre. The specimen was mounted vertically below the disc and connected to the lead at one end. The other end was held in a small steel bracket soldered to a rod suspended from the disc. The specimens had the shape of a ribbon 2~ cm. long, 0.125 ram. thick and 4 mm. wide. The central portion was reduced to a width of 1 rnm, over a length of about 1 cm. and was twisted so t h a t one ½ t u r n was completed in the area exposed to the X - r a y beam. I n this way the same diffraction p a t t e r n was obtained as if a wire specimen was used. The vacuum case holding the specimen consisted of a brass cylinder 3.5 cm. long and 2.5 cm. wide, sealed off a t one end and bolted with a flange to the brass disc at the other. The observation window was S ram. × 200 ° which permitted only half of the conventional symmetrical powder photograph to be taken. Thus only 2 / 3 of the normal film length were. required. No accurate temperature measurements were needed in this particular application b u t there was enough room for a n optical pyrometer to be sighted through the space left in the window. An oil diffusion p u m p unit was used for t h e evacuation of the chamber to 0.1/~. Photographs a t temperatures up to 1,000°C. were t a k e n with this unit. The exposure periods lasted up to 2 hours. Sommaire : Ddtaiis sur un appareillage spdcial p o u v a n t ~tre utilis6 avec une camdra ordinaire pour la prise d'images de diffraction ~ h a u t e teml~rature, d'dchantillons d'acier, alors que l'on ne dispose pas d'une cam6ra pour hautes teml~ratures.
Abst~t ~o. and References
Article by M. Auwaerter P/a~ee Proe. 1952
1-7
Note by Anon. D u ~ & -~u. C~a~-e B~J. No. 14 Nov. 1952 5
e4/I
Letter by H. T. Heal,
E. Gill~m & D. O. Cole 3. ~e/. In:b~un. 29, Nov. 1952 880-381
Impregnation Improves Casting Quality See Abstract No. : 32/III
05/1
The Electrical Resistivity of Thin Tin Films with Lattice Defects See Abstract No. : 20/111
e0/1
x9 - -
SCIENCES
(other than the above) --
x9
Introduction to the Vacuum Concrete Process See Abstract No. : 48/III Plight-Tone and Wing-Stroke Frequency of Insects and the Dynamics of Insect Flight Finland. Various methods are available for t h e determination of wing-stroke frequency in insects, for instance t h e kymograph and the chronophotographic method. The acoustic method which determines the wing-stroke frequency (v) b y the flight-tone is rarely used although it can be very exact and permits observation of the insect in free flight. The wing-stroke frequency of insects varying from 0 to 1,000 per sec. is known to be related to the wing and body dimensions and to the wing-stroke angle. There m a y be also a dependence on temperature, b u t a dependence on atmospheric pressure has never been proved conclusively. Chadwick has Shown t h a t the wing-stroke frequency in Drosophila is an indicator of energy ..consumption generally and t h a t this method can be used for a quantitative approach to the .dynamics of insect flight. Two series of experiments were carried out. I n the first series, conducted a t atmospheric pressure, the following relationship between wing-stroke frequency (v) and inertia (I).was established : v oc I-0.gs + 0.0s. I n the second series t h e insects were flying in a bell jar which could be evacuated b y a water jet pump. As before, the frequency was determined b y acoustic methods with the aid of a microphone placed inside the bell jar. The results established the relationship : v oc p ° ~ . The exponent depends on the size a n d frequency of the wing-shake. The above observations permit the development of a mathematical expression for the energy used b y the insect to keep the wings in motion and permit t h e t e n t a t i v e conclusion t h a t t h e m~i- work done b y t h e insect is directed against overcoming wing-inertia. The effect of the surrounding air pressure m a y v a r y b u t accounts for less t h a n 1% of t h e t o t a l effort. Sommaive: L a dy~amique d u vol d'ineectes a 6t~ 6tudi~e th6oriquement a t exp&imentalement, faisant partiellement usage des proc6d~s de vide. January, 1953
Vacuum Vol. I I I No. I
e8/1
Note by O. Sotavalta Na$ure z7ot_ 20.12.52 1057-1068
78
I
--
General Science a n d Engineering. C~td.
--
I
chamber increased initially due to the dissociation of the oxygen b u t after a short while decreased again indicating t h a t the speed of diffusion of the oxygen from t h e interior of the body of the metal was slow. I t appears advisable therefore to reduce metal before it is sintered. Normal protective atmospheres are of little use in these operations as their partial oxygen pressure is comparatively high. The sintering of ceramics in a high vacuum is not necessarily an advantage. During the sintering process a partial reduction of the oxygen compound m a y take place and the finished product m a y no longer be of the required composition. Sommaire: Yes causes et le mdcanisme des changements chimiques, ~ l'int~rieur de compos~s d'oxydes m6talliques, lors de l'6vaporation sont ~tudi6s. Important Steps in Investment Casting United Kingdom. A brief description is given of the main exhibit of the Design and Research Centre a t the British Industries Fair, 1952. The subject was investment casting. Each step in the process of manufacturing jewellery b y this method was illustrated b y an exl~ibit of the production apparatus required. Nine steps were shown : (1) Making the Master Model, (2) Making the R u b b e r Moulds, (3) W a x Injector, (4) Mounting the W a x Pattern, (5) Selecting a Suitable Investment, (6) Investing, (7) Burning Out, (8) Casting and (9) Knocking out. Under (6) reference was made to the p a r t v a c u u m plays in the process. Sommaire : Br~ve note concernant l'ordre des opdrations dans la m6thode de moulage ~ la cite perdue. A Powder Camera Modification for High Temperature P h o t o g r a p h s United Kingdom. The design of a unit is described which facilitates th~ taking of high temperature powder photographs of steel specimens in the form of thin strips with the help of a n ordinary camera. I t consists of a 9 cm. diameter brass disc with a current lead a t the centre. The specimen was mounted vertically below the disc and connected to the lead at one end. The other end was held in a small steel bracket soldered to a rod suspended from the disc. The specimens had the shape of a ribbon 2~ cm. long, 0.125 ram. thick and 4 mm. wide. The central portion was reduced to a width of 1 rnm, over a length of about 1 cm. and was twisted so t h a t one ½ t u r n was completed in the area exposed to the X - r a y beam. I n this way the same diffraction p a t t e r n was obtained as if a wire specimen was used. The vacuum case holding the specimen consisted of a brass cylinder 3.5 cm. long and 2.5 cm. wide, sealed off a t one end and bolted with a flange to the brass disc at the other. The observation window was S ram. × 200 ° which permitted only half of the conventional symmetrical powder photograph to be taken. Thus only 2 / 3 of the normal film length were. required. No accurate temperature measurements were needed in this particular application b u t there was enough room for a n optical pyrometer to be sighted through the space left in the window. An oil diffusion p u m p unit was used for t h e evacuation of the chamber to 0.1/~. Photographs a t temperatures up to 1,000°C. were t a k e n with this unit. The exposure periods lasted up to 2 hours. Sommaire : Ddtaiis sur un appareillage spdcial p o u v a n t ~tre utilis6 avec une camdra ordinaire pour la prise d'images de diffraction ~ h a u t e teml~rature, d'dchantillons d'acier, alors que l'on ne dispose pas d'une cam6ra pour hautes teml~ratures.
Abst~t ~o. and References
Article by M. Auwaerter P/a~ee Proe. 1952
1-7
Note by Anon. D u ~ & -~u. C~a~-e B~J. No. 14 Nov. 1952 5
e4/I
Letter by H. T. Heal,
E. Gill~m & D. O. Cole 3. ~e/. In:b~un. 29, Nov. 1952 880-381
Impregnation Improves Casting Quality See Abstract No. : 32/III
05/1
The Electrical Resistivity of Thin Tin Films with Lattice Defects See Abstract No. : 20/111
e0/1
x9 - -
SCIENCES
(other than the above) --
x9
Introduction to the Vacuum Concrete Process See Abstract No. : 48/III Plight-Tone and Wing-Stroke Frequency of Insects and the Dynamics of Insect Flight Finland. Various methods are available for t h e determination of wing-stroke frequency in insects, for instance t h e kymograph and the chronophotographic method. The acoustic method which determines the wing-stroke frequency (v) b y the flight-tone is rarely used although it can be very exact and permits observation of the insect in free flight. The wing-stroke frequency of insects varying from 0 to 1,000 per sec. is known to be related to the wing and body dimensions and to the wing-stroke angle. There m a y be also a dependence on temperature, b u t a dependence on atmospheric pressure has never been proved conclusively. Chadwick has Shown t h a t the wing-stroke frequency in Drosophila is an indicator of energy ..consumption generally and t h a t this method can be used for a quantitative approach to the .dynamics of insect flight. Two series of experiments were carried out. I n the first series, conducted a t atmospheric pressure, the following relationship between wing-stroke frequency (v) and inertia (I).was established : v oc I-0.gs + 0.0s. I n the second series t h e insects were flying in a bell jar which could be evacuated b y a water jet pump. As before, the frequency was determined b y acoustic methods with the aid of a microphone placed inside the bell jar. The results established the relationship : v oc p ° ~ . The exponent depends on the size a n d frequency of the wing-shake. The above observations permit the development of a mathematical expression for the energy used b y the insect to keep the wings in motion and permit t h e t e n t a t i v e conclusion t h a t t h e m~i- work done b y t h e insect is directed against overcoming wing-inertia. The effect of the surrounding air pressure m a y v a r y b u t accounts for less t h a n 1% of t h e t o t a l effort. Sommaive: L a dy~amique d u vol d'ineectes a 6t~ 6tudi~e th6oriquement a t exp&imentalement, faisant partiellement usage des proc6d~s de vide. January, 1953
Vacuum Vol. I I I No. I
e8/1
Note by O. Sotavalta Na$ure z7ot_ 20.12.52 1057-1068
78