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Advances in MEMS technology have resulted in relatively low cost gyroscopes and accelerometers and, correspondingly, inexpensive inertial measurement systems. This has opened up the field of applications for inertial measurement units (IMUs) and they are currently being proposed for use in a wide variety of possible applications, with environmental conditions ranging from mild to harsh. Of particular interest in this study are MEMS gyroscopes, which are based upon vibratory, rather than rotational, designs and are especially susceptible to the effects of acoustic noise, as compared to conventional gyroscopes. This is particularly true for certain applications. For example, in some aerospace environments, noise levels can be greater than 120 dB and extend over a frequency range greater than 20 kHz. Output signals can be overwhelmed by such effects, becoming extremely contaminated and noisy and, can even be completely saturated. So, it is important to develop an understanding of the influence of high levels of noise on MEMS gyroscope performance and to develop methodologies to mitigate such effects. In the present investigation, a series of experimental studies were conducted for a variety of MEMS gyroscope designs. Each unit was exposed to a range of acoustic noise amplitudes and frequencies. The output signals were recorded and analyzed. The results are presented and discussed in detail. Strategies for mitigating such effects were identified and tested. Those results are also discussed in detailed.

The field of composite materials is a rapidly developing and expanding area, with new innovations and discoveries occurring almost daily, producing new available materials, processing techniques, fabrication methods, and applications. This article reviews recent innovations and developments in this field with a specific focus on syntactic and metal foams. Recent work is identified and placed in context with regard to other work in the area. A summary discussion of the implications of this work and potential applications is also provided.