226 Acoustic Emission The resistance Rmand capacitance Cmof the mixture flowing through the pipe depends on the permittivity and conductivity of the oil, water and gas components, the void fraction and water fraction of the flow, and the flow regime. The application of acoustic emission to non-destructive testing of materials typically takes place between 20 kHz and 1 MHz. [5] Unlike conventional ultrasonic testing, AE tools are designed for monitoring acoustic emissions produced by the material during failure or stress, and not on the material's effect on externally generated waves. The four -credit (forty hours) Acoustic Emission course was developed for Drexel University s engineering technology (ET) and engineering students. The course presents principle s of Acoustic Emission (AE) Nondestructive Evaluation of Materials (NDE) , combining hands -on laboratory experience with lectures. we have organized the reviewbasedonthechemical orphysicaleffect ofultrasound exploited for the formation of nanomaterials: (1) primary sono- chemistry employing volatile precursors, (2) secondary sono- chemistry using non-volatile precursors, (3) materials created or modified through the physical effects of ultrasound (i.e., shock waves), and (4) … Injection-induced fracture processes in rock samples are monitored by using ultrasonic transmission and acoustic emission (AE) techniques. We injected water into dry, cylindrically shaped granite samples under constant differential stress and confining pressure. During water migration, we measured P- and S-wave velocities. Receiving displacement sensitivities (Rx) of ultrasonic transducers and acoustic emission (AE) sensors are evaluated using sinewave packet excitation method and compared to the corresponding data from pulse excitation method with a particular Introduction to Acoustic Emission. Acoustic emission is an amazing, promising and challenging subject of the modern technology and science. It is a well known from everyday life phenomenon: sound of breaking glass, falling tree, cracking ice are some examples of fracture sound we may hear from different objects subjected to stress. the stress. The development of such techniques accom- panied by semi-destructive methods like incremental hole-drilling technique is appropriate for stress measu- rement and health monitoring of the instruments. 1.1 Acoustic Emission Method Acoustic emission (AE) is the result of elastic propagation of waves generated in a material by rapid acoustic emission (ae) and ultrasonic sensors can detect transient sources of khz- to mhz-frequency vibrations that arise from source mechanisms ranging from tensile crack- ing (e.g. [1]) to shear slip events (e.g. [2,3]) to granular flow(e.g.[4]).quantitativecharacterization(i.e.calibration) of such sensors, allows researchers to link recorded … are discussed. Applications of acoustic emission technique for fatigue crack growth studies in 316 stainless steel and for on-line monitoring of forging of Al alloys are also discussed. 1.0 Introduction Non-destructive evaluation (NDE) techniques such as ultrasonic and acoustic emission are techniques based on the acoustic emission phenomenon. Depending on application type and, resulting from it, the frequencies of ultrasonic signals registered, transducers are divided into three categories: low frequency (20-100 kHz), standard frequency (