DIFFRACTIVE REFLECTION AND SCATTERING OF ULTRASONIC WAVES. THEIR INFLUENCE ON TORSION-PENDULUM MEASUREMENTS OF SOUND INTENSITY

1930 ◽  
Vol 3 (6) ◽  
pp. 491-509 ◽  
Author(s):  
R. W. Boyle ◽  
J. F. Lehmann

Light waves are too short and ordinary sound waves generally too long to permit experimental work on diffraction and scattering by a single small obstacle. An opportunity for such work however is presented in the case of ultrasonic waves.This paper describes an experimental investigation on the factors which determine the diffractive reflection and scattering of an ultrasonic wave train by plane circular opaque discs, and discusses the results. These are of special importance in the measurement of sound energy intensity by the torsion-pendulum method, for such measurements should always be corrected to allow for the effect of diffractive scattering of the energy by the measuring-pendulum vane. The correction factor will depend on the size and form of the pendula vanes employed and for circular vanes can be obtained directly from such curves as are shown in this paper as results of the investigation.

1936 ◽  
Vol 14a (8) ◽  
pp. 158-171 ◽  
Author(s):  
F. H. Sanders

Measurements of the distribution of light energy among the various orders of the diffraction pattern produced when monochromatic light is passed through a liquid subjected to high-frequency ultrasonic disturbances have been carried out over a range of ultrasonic intensities at frequencies in the region of 5 megacycles per second. Both progressive and standing wave fields have been studied. Results of the experiments show excellent agreement with the theory of Raman and Nath for the variation in degree of scattering with varying ultrasonic intensity. Absolute measurements of the sound intensity conducted with a torsion pendulum are in good agreement with that expected from the theory for the liquids and light wave-lengths involved.


2019 ◽  
Vol 3 (2) ◽  
pp. 131-141
Author(s):  
Evan Hanks ◽  
Anthony Palazotto ◽  
David Liu

Purpose Experimental research was conducted on the effects of surface roughness on ultrasonic non-destructive testing of electron beam melted (EBM) additively manufactured Ti-6Al-4V. Additive manufacturing (AM) is a developing technology with many potential benefits, but certain challenges posed by its use require further research before AM parts are viable for widespread use in the aviation industry. Possible applications of this new technology include aircraft battle damage repair (ABDR), small batch manufacturing to fill supply gaps and replacement for obsolete parts. This paper aims to assess the effectiveness of ultrasonic inspection in detecting manufactured flaws in EBM-manufactured Ti-6Al-4V. Additively manufactured EBM products have a high surface roughness in “as-manufactured” condition which is an artifact of the manufacturing process. The surface roughness is known to affect the results of ultrasonic inspections. Experimental data from this research demonstrate the ability of ultrasonic inspections to identify imbedded flaws as small as 0.51 mm at frequencies of 2.25, 5 and 10 MHz through a machined surface. Detection of flaws in higher surface roughness samples was increased at a frequency of 10 MHz opposed to both lower frequencies tested. Design/methodology/approach The approach is to incorporate ultrasonic waves to identify flaws in an additive manufactured specimen Findings A wave frequency of 10 MHz gave good results in finding flaws even with surface roughness present. Originality/value To the best of the authors’ knowledge, this was the first attempt that was able to identify small flaws using ultrasonic sound waves in which surface roughness was present.


2017 ◽  
Vol 42 (3) ◽  
pp. 499-506 ◽  
Author(s):  
Małgorzata Szymiczek

AbstractObservation of behaviour phenomena of ultrasonic waves in an object allows for quality assessment, identification and location of discontinuity. Physical nature of acoustic processes is based on propagation of mechanical waves constituting a disturbance of equilibrium of the state of material. The acoustic process identified by selected characteristics can be a source of information about state of material, its structure, and properties, which is particularly important for systems exhibiting anisotropy properties, and such are layered polymer composites. They are special materials because their properties depend greatly on the manufacturing technology. Therefore, while conducting acoustic tests which use the influence of elastic properties and homogeneity of material structure for propagation of sound waves the adopted method of measuring characteristics which identifies propagation of ultrasonic wave phenomenon is of particular importance. The aim of the work was quality evaluation of layered polymer composites made by winding and press moulding by the method of echo and C-scan, using head Phased Array. Composites have been tested by thermal and fatigue degradation. Quality evaluation has been made based on the transition time of the ultrasonic wave and the bending strength.


Author(s):  
Monisha Veeravani

Music gives people a deeper understanding on the level of sensation and motivates them to become better and this element can change the world when it is wider than our own. It is music that connects the beginning to the end and becomes the literature of our heart. Fills the soul with affection, takes the mind from deep darkness to eternal heights. Music has the status of a® God, so purity has special importance in this genre. Music is the way to cultivate the mind through the seven pure and five vocal cords. Therefore, it can be said that music is necessary to keep the body and mind healthy, cheerful. This keeps the body, mind and brain healthy, and concentrates. Stress is also removed from music. It has been proved by various scientific experiments that both music practice and yoga practice develop strength in human life and many diseases can be treated. Music therapy i.e. music therapy nowadays plays an important role in relieving many health problems. Is playing If you live under high stress or are suffering from insomnia problem, then you can take help of this therapy. Each sound produces specific waves. These sound waves directly affect our brain. Everything in existence is affected by these waves. If a music is composed with the right words and the appropriate ragas, it will work on our brain in the same way that the software works inside a computer. Since our entire body is under the control of the brain, we can get the right result by having the expected effect on the brain through remedial music. संगीत लोगों को संवेदना के स्तर पर एक गहरी समझ देकर उन्हें बेहतर बनने की दिशा में प्रेरित करता है और यही तत्व जब निज से व्यापक होता है तो दुनिया भी बदल सकती है. ये संगीत ही है जो आदि को अंत से जोडकर हमारे हृदय का साहित्य बन जाता है। आत्मा को स्नेह से भर देता है मन को गहन अन्धकार से लेकर अनन्त ऊंचाइयों तक ले जाता है । संगीत क® ईश्वर का दर्जा प्राप्त है, इसीलिए इस विधा में शुध्दता का विशेष महत्व है। सात षुघ्द अ©र पांच क®मल स्वर®ं के माध्यम से मन क® साधने का उपाय है संगीत। अतः कहा जा सकता है कि शरीर तथा मन क® स्वस्थ््ा, प्रफुल्लित रखने के लिए संगीत आवश््यक है। इससे शरीर, मन, मस्तिष्क स्वस्थ््ा रहता है, एकाग्र रहता है। संगीत से तनाव भी दूर ह®ता है। विभिन्न वैज्ञानिक प्रयोगों द्वारा यह सिद्ध हो चुका है कि संगीत साधना व योग साधना दोनों से मनुष्य के जीवन में शक्ति का विकास होता है और अनेक बीमारियों का उपचार किया जा सकता है म्यूजिक थेरेपी यानी संगीत चिकित्सा आजकल अनेक स्वास्थ्य समस्याओं से राहत दिलाने में अहम भूमिका निभा रही है। आप अगर ज्यादा तनाव में रहते हैं या अनिद्रा की समस्या से पीडित हैं तो इस चिकित्सा की सहायता ले सकते हैं । हर ध्वनि से विशिष्ट तरंगें पैदा होती हैं। ये ध्वनि तरंगें सीधे हमारे मस्तिष्क को प्रभावित करती हैं। इन्हीं तरंगों से अस्तित्व में मौजूद हर चीज प्रभावित होती है। अगर कोई संगीत सही शब्दों और उपयुक्त रागों के साथ तैयार किया जाए तो वह हमारे मस्तिष्क पर उसी तरह काम करेगा जैसे किसी ’कम्प्यूटर’ के अंदर ’साफ्टवेयर’ काम करता है। चूंकि हमारा पूरा शरीर मस्तिष्क के नियंत्रण में होता है, इसलिए हम मस्तिष्क पर उपचारी संगीत के माध्यम से अपेक्षित प्रभाव डालकर सही परिणाम प्राप्त कर सकते हैं।


2005 ◽  
Vol 872 ◽  
Author(s):  
Kazuhiro Suzuki ◽  
Hideyuki Funaki ◽  
Yujiro Naruse

AbstractWe present a new conceptual active optical microphone based on complementary metal-oxide semiconductor (CMOS) - micro electro mechanical systems (MEMS) micromachining techniques. The diaphragm of the microphone has a diffracting grating fabricated by the CMOS process with only a small number of post-processes. The active microphone actuates the diaphragm on an arbitrary frequency by electrostatic force, and detects sound waves by the light waves. From the verification experiment result, this active microphone was able to perform advanced functions, such as the amplifier effect and the detection of phase information of sound waves.


In this paper, the electrical effects accompanying the propagation of sound waves through a suspension of spherical colloidal particles in an electrolyte are examined. It is shown that, for charged colloidal particles, differences of potential arise between different points in the wave train. A general method is given for obtaining the amplitude of the potential difference in the case when the thickness of the double-layer surrounding the particles is small compared with the particle radius, as a power series in the zeta-potential and the leading term in this series is evaluated, so that the results will be adequate for zeta-potentials which are not too large. An exact expression is obtained for the case when the thickness of the double-layer is very much greater than the particle radius but still much less than the mean separation. An attempt is also made to estimate the effect for intermediate values of the double-layer thickness. The amplitude of the potential difference decreases with increasing concentration of electrolyte and, when measured between points a half-wave-length apart, is substantially independent of the frequency of the sound waves, except at very high frequencies. The results are compared with the experimental data.


1965 ◽  
Vol 3 (7) ◽  
pp. 330-331
Author(s):  
Winston E. Kock ◽  
J. W. Buchta
Keyword(s):  

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