Sonoorganic Synthesis Engineering

2001 ◽  
Author(s):  
L. K. Doraiswamy
Keyword(s):  
Scale Up ◽  
Reaction Rates ◽  
Hydrodynamic Cavitation ◽  
Sound Waves ◽  
Alternative Means ◽  
Normal Human ◽  
Hearing Range ◽  
Human Hearing ◽  
Human Ear ◽  
Economic Considerations

Ultrasonics or ultrasound refers to sound waves beyond the audible range of the human ear. The normal human hearing range is 16-16,000 cycles per second. The accepted terminology for one cycle per second is the Hertz (or Hz), and hence the hearing range is expressed as 16 Hz to 16kHz. Ultrasound is normally considered to lie approximately in the range of 15kHz to 10 MHz, that is, 15 x 103 to 10000 x 103 cycles per second, with acoustic wavelengths of 10 to 0.01 cm. Like any sound wave, ultrasound is propagated through a medium in alternating cycles of compression and stretching or rarefaction. These produce certain effects in the medium that can be usefully exploited. One such application is in the field of synthetic organic chemistry, first reported by Richards and Loomis (1927) and designated sonochemistry. The most appealing feature of sonochemistry is its ability to enhance reaction rates, often to remarkably high levels under environmentally benign conditions. Despite this potential, economic considerations have precluded the use of sonochemical processes. It is noteworthy, however, that a change in perspective appears to be emerging, as evidenced by the fact that a pilot plant is currently being funded by a French company to sonochemically oxidize cyclohexanol to cyclohexanone, and developmental work is underway in Germany to produce 4 tons of Grignard reagent per year (Ondrey et al., 1996). A number of books and reviews covering mostly the chemical aspects of sonochemistry have appeared over the years, for example, Suslick, 1988, 198, 1990a,b; Ley and Low, 1989; Mason, 1986, 1990a,b, 1991; Mason and Lorime 1989; Price, 1992; Bremner, 1994; Low, 1995; Luche, 1998. A recent review Thompson and Doraiswamy (1999) covers both the chemical and engineering aspects of sonochemistry and another by Keil and Swamy (1999) examines the present state of our understanding of sonoreactor design. Sonochemical enhancement of reaction rates is caused by a phenomenon called cavitation. Therefore, we largely confine the treatment in this chapter to the chemical and reaction engineering (scale-up) aspects of cavitation and its associated effects (see Shah et al., 1999, for a detailed treatment). An alternative means of achieving the same result is by mimicking the ultrasonic effect by inducing “hydrodynamic cavitation.”

Application of the Electrostatic Micro-Speakers for Producing Audible Directional Sound

2020 ◽  
Vol 12 (04) ◽  
pp. 2050045
Author(s):  
Mohammad Homaei ◽  
Mohammad Fathalilou ◽  
Rasoul Shabani ◽  
Ghader Rezazadeh
Keyword(s):  
Radiation Pattern ◽  
Mechanical Systems ◽  
Sound Radiation ◽  
Sound Power ◽  
Sound Waves ◽  
Radiation Patterns ◽  
Micro Electro Mechanical Systems ◽  
Hearing Range ◽  
Human Hearing ◽  
Square Array

In recent years, the demand for control of sound power and radiation patterns in personal messaging, calls, automotive entertainment, and gaming has brought a new interest in the audio world. The aim of this paper is to investigate the feasibility of producing the sound waves in the audible range and directing them in the desired listening zone by electrostatic micro-speakers. Therefore, a capacitive circular micro-plate has been modeled as an electrostatic micro-speaker. Then a Bessel panel array has been developed using a number of these plates arranged in a square array. The equations governing the vibrations of the micro-speaker’s diaphragm, as well as radiation pattern of the sound waves, have been introduced and solved. The results have shown that the Micro-Electro Mechanical Systems (MEMS) electrostatic diaphragms have the capability of producing the directional sound in the human hearing range. Moreover, we have investigated the effect of different excitation frequencies, radii size and the number of the diaphragms as well as the inter-element spacing on the sound radiation pattern of the Bessel panel array.

scholarly journals The Basics of Ultrasonography

2017 ◽  
Vol 46 (1) ◽  
pp. 44-47
Author(s):  
Sabrina Q Rashid
Keyword(s):  
Human Body ◽  
The Body ◽  
Sound Waves ◽  
Internal Organs ◽  
Ultrasound Waves ◽  
Internal Structures ◽  
Hearing Range ◽  
Human Hearing ◽  
Different Tissues

Ultrasound is sound whose frequency is above the human hearing range. It is nowadays widely used for the evaluation of a patient’s internal organs. Ultrasound waves are transmitted into the human body by an instrument called the transducer. Inside the body the sound waves are reflected and scattered differently by the different tissues and organs. The reflected sound waves are used by the computer to form an image of the internal structures and tissues. Use of ultrasound is safe with negligible bio-effects.Bangladesh Med J. 2017 Jan; 46 (1): 44-47

scholarly journals An Update on Applications of Power Ultrasound in Drying Food: A Review

2019 ◽  
Vol 8 (1) ◽  
pp. 29-38 ◽  
Author(s):  
Vahid Baeghbali ◽  
Mehrdad Niakousari ◽  
Michael Ngadi
Keyword(s):  
Nutritional Value ◽  
Synergistic Effects ◽  
Drying Methods ◽  
Sound Waves ◽  
Power Ultrasound ◽  
History Of ◽  
Hearing Range ◽  
Human Hearing ◽  
Drying Conditions

Ultrasound is sound waves with above the human hearing range frequency that is approximately 20 kHz. Application of power ultrasound in combination with other food processing methods including drying, is considered to be an emerging and promising technology. The use of novel non-thermal technologies, such as power ultrasound, is suitable to facilitate the drying of heat sensitive food materials. Ultrasound enhance heat and mas transfer which result in faster moisture removal during drying due to heating, vibration and synergistic effects. These effects could lead to product quality preservation in terms of color, texture, vitamin C and antioxidants content, by the use of milder drying conditions, and in some cases can promote better energy efficiency. In this article, after a brief review on the history of ultrasonic drying, different methods are categorized and combinations of ultrasound with novel drying methods and their effects on phytochemicals are discussed with the focus on the recently published articles. Studies showed that the quality of ultrasonically dried products was usually higher than conventionally dried products. However, the effect of ultrasonic drying on the texture and nutritional value of the products should be further investigated.

Uses of ultrasonic cleaners in paleontological laboratories

1989 ◽  
Vol 4 ◽  
pp. 213-217 ◽  
Author(s):  
John Pojeta ◽  
Marija Balanc
Keyword(s):  
Mechanical Energy ◽  
Electrical Energy ◽  
Soft Materials ◽  
Low Pressure ◽  
Pressure Waves ◽  
Sound Waves ◽  
Ultrasonic Cleaning ◽  
Cleaning Solution ◽  
Rubber Cloth ◽  
Human Hearing

Ultrasonic cleaning is a fast and usually safe method for cleaning many hard objects that are not glued together, and it is thus useful in paleontological laboratories. It is relatively ineffective for cleaning soft materials such as rubber, cloth, and fibers. Ultrasonic cleaning machines use sound waves, or mechanical vibrations, that are above the human hearing range, and operate at frequences up to 55,000 cycles per second. The sound waves are generated by a transducer (Figure 1), which changes high frequency electrical energy to mechanical energy. This mechanical energy, or vibration, is then coupled into the liquid in the cleaning tank. The vibrations cause alternating high and low pressure waves in the liquid. This action forms millions of microscopic bubbles, which expand during low pressure waves and form small cavities. During the high pressure waves, these cavities collapse, or implode, creating a mechanical scrubbinglike action, which loosens dirt on all surfaces in contact with the cleaning solution. This action can take place up to 55,000 times a second, making it seem as though the dirt is being blasted from the surface and cavities of the object being cleaned. Ultrasonic cleaning is effective wherever capillary action will take the solution. Complete cleaning usually requires from 30 seconds to two minutes (Anonymous, 1983).

XVIII Tolerance of the Normal Human Ear to Topical Dimethyl Sulfoxide

1966 ◽  
Vol 75 (1) ◽  
pp. 208-215 ◽  
Author(s):  
Charles P. Lebo ◽  
Paul E. Poenisch ◽  
William S. McAfee
Keyword(s):  
Dimethyl Sulfoxide ◽  
Normal Human ◽  
Human Ear

Influence of Orifice Shape on Reaction Rate by Hydrodynamic Cavitation

2014 ◽  
Vol 625 ◽  
pp. 718-721 ◽  
Author(s):  
Keiji Yasuda ◽  
Toa Kaji ◽  
Zheng Xu
Keyword(s):  
Reaction Rate ◽  
Reaction Rates ◽  
Hole Diameter ◽  
Orifice Plate ◽  
Hydrodynamic Cavitation ◽  
Hole Area ◽  
Upstream Pressure ◽  
Shaped Hole

Hydrodynamic cavitation is expected to apply to the decomposition of chemicals and the disinfection in wastewater. In this study, the effects of upstream pressure, hole diameter and shape of orifice plate on the reaction rate of I3- formation were investigated. The reaction rate increases with increasing upstream pressure of orifice plate. The reaction rates have maximum values, when hole diameters of orifice plate are 2.7 mm at the upstream pressure of 0.9 MPa gauge and 3.0 mm at 0.7 MPa gauge. The reaction rate increases in the order of triangle < square < hexagon < circle shaped hole of orifice plate at the same hole area.

Ultrasonography in Children

PEDIATRICS ◽  
1974 ◽  
Vol 54 (4) ◽  
pp. 480-481
Author(s):  
Herman Grossman ◽  
Alvin Felman ◽  
John A. Kirkpatrick ◽  
Charles H. Shopfner ◽  
Leonard E. Swischuk ◽  
...  
Keyword(s):  
Pediatric Patients ◽  
Mechanical Vibration ◽  
Diagnostic Technique ◽  
Diagnostic Study ◽  
Sound Waves ◽  
Valve Motion ◽  
Acquired Heart Disease ◽  
Ventricular Wall Thickness ◽  
Human Hearing ◽  
Pass Through

Ultrasound is the manifestation of a high frequency mechanical vibration. The sound waves produced are beyond the range of human hearing, i.e., 1 to 10 mHz. The sound waves travel through liquids and solids but cannot pass through air or vacuum. Ultrasonic energy is produced by a transducer, the power to which is supplied by a high-voltage pulsing circuit in an amplifier (ultrasonoscope). Ultrasonography has been used successfully in the examination of pediatric patients. One of the most common uses has been to measure shifts of the midline structures of the brain. By utilizing the standard echoencephalographic approach established for adults, and positioning the transducer above the ears in the temporoparietal regions, echoes are recorded from the midline structures. Ultrasonography is used as a preliminary study prior to more definitive procedures such as pneumoencephalography or arteriography, particularly in the presence of localizing signs. It has also been used to detect hydrocephalus and to follow changes in ventricular size which occur after ventricular shunting procedures. In fact, this is the easiest way to serially monitor the response to decompression. In many hospitals, ultrasonagraphy is considered to be the primary diagnostic study for the detection of pericardial effusion. Ultrasonic examination of the heart of pediatric patients with suspected congenital or acquired heart disease appears to be a promising new diagnostic technique. It has been successfully used to evaluate a number of abnormalities: great vessel transposition, cardiac chamber size and position, valve motion, and ventricular wall thickness. Extensive research is in progress to establish both normal values and patterns for differentiating various congenital abnormalities.

Advances in biofilm aerobic reactors ensuring effective biofilm activity control

1994 ◽  
Vol 29 (10-11) ◽  
pp. 319-327 ◽  
Author(s):  
V. Lazarova ◽  
J. Manem
Keyword(s):  
Scale Up ◽  
Reaction Rates ◽  
The State ◽  
Effective Control ◽  
Principal Characteristics ◽  
Biofilm Thickness ◽  
Advantages And Disadvantages ◽  
Mobile Bed ◽  
Three Phase ◽  
Biological Reaction

Increasing volumes of wastewaters combined with limited space availability and progressively tightening standards and quality control, promote the development of new intensive biotechnologies for water treatment. Fixed biomass processes offer several advantages compared with conventional biological treatments, respectively, higher volumetric load, increased process stability and compactness of the reactors. The purpose of this paper is to present an overview of the principal characteristics of advanced aerobic biofilm processes (performance, reactor configurations, scale-up, energy consumption, field of application, etc.), completed by a synthesis of their advantages and disadvantages. Emphasis is placed on the factors and techniques ensuring effective control of biofilm thickness and better mass transfer. For better understanding of biofilm processes, a new bioreactor classification is proposed as a function of the state of the biomass, the state of the medium and the hydrodynamic conditions. The control of the biofilm thickness is recognized as one of the most important parameters influencing process performance and efficiency. It is concluded that three-phase bioreactors ensure enhanced biological reaction rates through an effective biofilm control. However, further studies are needed to develop new economically attractive full scale mobile bed bioreactors.

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