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How to decrease noise and vibration exposure has been of interest for many years. Empirical data have indicated that too high dose values can create multiple problems to a human body - often severe. Some years back, the European Machinery Directive has increased the responsibility for manufacturers and employers to make sure limits are complying with legislation. Classical technology often consists of passive solutions aiming at trying to cut back on noise and vibration levels. For low frequency, these methods are often lacking the needed performance especially if weight should be considered at the same time. A smart combination of passive and active techniques can make a real difference. Today, with possibilities for low cost and embedded electronics and the rapid development of new actuators, a vast range of applications are possible for this combined combat approach, with a financial advantage as well.

In applications for acoustic profiling, an analysis of current versus depth is key. By analyzing the Doppler frequency variation in the backscattering signal, it is possible to calculate the mean current versus depth. However, due to turbulence in the water creating simultaneous currents and layers, the current direction could change rapidly, making the data non-stationary and difficult to analyze. The transmitted pulse is very short, and the volume where the current should be estimated is typically small. Also, the water volume can contain multiple Doppler responses due to turbulence and other phenomenon. W hen using this innovative non-linear filtering method, Multiple Peak Count Analysis, these effects can become visible, and the method shows superior performance as compared to classical methods. Classical 3-dimensional spectral plots of the data, does not use a-priori information.

Chatter vibrations are causing large monetary losses daily in industry. New materials have increased the challenges with harmful vibration levels. Since the vibrations, when observed as a final result, are chaotic and the vibration process nonlinear, it is a challenging task to deal with it. It is also a common “understanding” in the cutting industry that chatter is RPM (the rotational speed) dependent, since the behavior changes with RPM. Many attempts have been done over many years to mitigate and understand the vibrations. In our vast research on these topics, we have found that it is rewarding to classify the vibrations into categories, enabling a better understanding of its underlying physics and “source of vibrations,” and thus also the formulation of a possible remedy. An analysis approach has been developed where vibrations are analyzed and categorized and a GO/NOGO indicator is telling if the machine has the “right type of vibrations.”