Noise Reduction Strategy

The goals set for the acoustic risk minimization process must be based on the fact that noise mnst be rednced to the lowest levels possible (allowed). These values could 

Noise reduction may be realized by means of a variety of technical measures. The measures include source noise reduction (e.g. noise generated by machines, woiking processes and procedures), noise reduction by noise absorption (e.g. by nsing shields, screens, absorbing panelling), noise reduction on designated locations (e.g. soundproof cabins, personal ear-protective equipment). 

Snccessful noise reduction depends on active and committed involvement of the company s management. 

Priority must be given to the prevention defined by legal enactments, snch as Directive No. 42/2006/EC, on machinery. A machine in compliance with the directive must be designed and constructed so that risks caused by airborne noise emissions are reduced to the lowest levels possible with respect to scientific knowledge and technology as well as availability of means for noise rednction, especially at the source of the noise. The noise emission levels may be assessed nsing comparative data on noise emissions for similar machine eqnipment. 

The user s manual, according to Directive No. 42/2006/EC on machinery, must include  

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Fowler, A. M. and Gatley, L 1991, Noise reduction strategy for hybrid IR focal plane arrays , SPIE Infrared Sensors Detectors, Electronics, and Signal Processing, 1541... 

PCA is a useful tool not only for visualizing information it can also be employed as a strategy for feature reduction and noise reduction, as indicated in Section Vl.C. 

Neuroradiologists are familiar with factors that affect patient dose such as pitch, milliamperes (mA), kilovoltage peak (kVp), and collimation, but there are additional ways to further reduce radiation exposure. The combination of low kilovolt peak (80 kVp) with low milliamperes-seconds (no more than 200 mAs) has already been noted and is an accepted strategy for dose reduction [36, 87, 88]. (Tube current is directly proportional to dose, but at a cost of increased noise, which is increased by 1/VmA). In our institution, we recently lowered the mAs of our CTP protocol from 200 to 150 mA resulting in 25% dose reduction, previously estimated at 0.47 Gy (the FDA suggests 0.5 Gy as the upper dose limit for a CTP study). Table 5.4 summarizes the radiation parameters of the sample CTP protocol of Tables 5.2 and 5.3. 

Category III noise Is reduced by strategies combining optimization of both detector and non-detector hardware as In reduction of reciprocating pump pulsation, the use of low thermal coefficient, matched pairs of photodiodes for reference and sample beam optical trains, and thermal coupling of reference and sample photodiodes. Pump pulsation noise can also be reduced by proper flow cell design ( ). 

The reasons for the main types of natural and cultural microseismic noise observed on land and strategies for their avoidance or reduction in seismic records are discussed in the following sections after a brief discussion on the principal difference between seismic signals and noise, their mathematical representation, and the correct way of comparison. 

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