Reducing Noise

If we assume that the analytical conditions have been optimized, say to produce maximum signal intensity, then any increase in signal-to-noise ratio 

---

Additional uses iaclude (/) filling the enclosed space ia double-pane wiadow units to reduce noise and heat transmission (87,88) (2) acting as a source of power from the reaction with lithium to produce heat (89,90) and (J) pressurizing recreation ball packages such as tennis balls to give improved shelfhfe (91). 

I oise Transmission Reduction in HVACSystems. One common use of sound-absorbing treatment is to reduce noise transmission in heating, ventilating, and air-conditioning (HVAC) systems (6). The treatments ate used to reduce the transmission of fan noise and air turbulence noise through ducts into occupied spaces. Noise transmission reduction in duct systems is described in terms of insertion loss, the difference in sound power level or sound pressure level measured at a given location before and after installation of the treatment or sound attenuation, the reduction in sound power between two locations affected by a sound source. The units ate decibels. 

Clean Air Act and its amendments ia 1970, 1977, and 1990 1967 Air Quahty Standards and National Air Pollution Acts and 1970 National Environmental PoHcy Act) (2) better waste disposal practices (1965 SoHd Waste Disposal Act 1976 Resource Conservation and Recovery Act) (see Wastes, industrial Waste treatment, hazardous wastes) (i) reduced noise levels (1972 Noise Control Act) (4) improved control of the manufacture and use of toxic materials (1976 Toxic Substances Control Act) and (5) assignment of responsibiUty to manufacturers for product safety (1972 Consumer Product Safety Act) (15,16). 

Property Modifiers. Property modifiers can, in general, be divided into two classes nonabrasive and abrasive, and the nonabrasive modifiers can be further classified as high friction or low friction. The most frequently used nonabrasive modifier is a cured resinous friction dust derived from cashew nutshell Hquid (see Nuts). Ground mbber is used in particle sizes similar to or slightly coarser than those of the cashew friction dusts for noise, wear, and abrasion control. Carbon black (qv), petroleum coke flour, natural and synthetic graphite, or other carbonaceous materials (see Carbon) are used to control the friction and improve wear, when abrasives are used, or to reduce noise. The above mentioned modifiers are primarily used in organic and semimetallic materials, except for graphite which is used in all friction materials. 

There is much interest and concern for noise/vibration-free brake systems and there is much activity toward friction couples having reduced noise/vibration properties. In addition to better noise insulators, brake modifications in the form of different materials, different designs, and improved friction materials formulations and/or processes are being developed and implemented. 

Lowering the inlet velocities and providing proper inlet silencers can reduce air noise. Considerable work by NASA on compressor casings has greatly reduced noise. 

Totally enclosed motors offer the highest degree of protection against moisture, corrosive vapors, dust, and dirt. TEWAC motors also have the advantage of reduced noise level. 

Apart from the energy constraints due to the friction losses, the main reason for limiting the air velocities in ducts is to reduce noise production. Some recommended air velocities are given in Table 9.9. 

This issue must be understood in order to reduce noise problems. 

Solvent pumped to wrong blender— contaminated batch Reduce noise levels. Reschedule operator tasks to reduce overload. Incorporate use of procedures in training scheme. 

Environmentally friendly. The reduced noise and lack ot air pollution is environmentally desirable, and so also IS the ability to climb steep grades and operate 111 smaller diameter tunnels. This combination is unbeatable by any other mode. 

To limit the pressure on the distribution system, so reducing noise and waste of water due to high-pressure mains and enabling higher-gauge and cheaper material to be used ... 

Because of their cellular or open-matrix construction, most insulants have an inherent ability to absorb sound, act as panel dampers and reduce noise breakout from plant by their ability to be a flexible or discontinuous link between an acoustically active surface and the outer cladding. This secondary aspect of thermal insulation specification will gain more prominence when the UK adopts the EC Directive 86/1888, Protection of workers from the risks related to exposure to noise at work . 

Finally, noise is also becoming of increasing concern, particularly on sites adjacent to urban areas. Acoustic enclosures, supplied by the manufacturer, will normally reduce noise levels to 85 dB, but if further reduction is required, attention must be paid to the material used to construct the buildings and enclosures low noise levels can be achieved only at a cost. 

Figure 34.14 An attempt to conceal tower and reduce noise, resulting in starvation of air and failure in performance...

TPEs range in hardness from as low as 25 Shore A up to 82 Shore D (Chapter 5, MECHANICAL PROPERTY, Hardness). They span a temperature of —34 to 17TC (—29 to 350°F), dampen vibration, reduce noise, and absorb shock. However,... 

Benefits CO2 sink (NR) Timber Land conservation Employment Employment Reduce noise Reduce vibration Energy transfer Contain liquids Fuel source raw materials ... 

Figure 4.19. Relative (top panel) and cumulative weight of material per size fraction for two different vendors (bottom panel A left B right). The cumulation helps reduce noise.

The SPRITE [16] technique was developed to reduce the dangerous mechanical vibrations and noise produced during an SPI experiment. In addition to the reduced noise and mechanical vibration, the experiment is much faster than SPI and the image intensity is still easily understood. However, one experimental shortcoming is a magnetic field gradient duty cycle which is even more demanding than an SPI experiment. 

Erode applied to a mask peels off a layer from every white island in the mask. Dilate does (almost) the inverse if erode has not managed to delete a white island completely, it is almost restored. The median operator reduces noise in the image without broadening the peaks. The operator is frequently addressed median filter . 

Molilat Lubricity additive containing molybdenum disulfide for improved resistance to wear, pitting and fretting. Reduces noise, increases maximum speed and engine life and cuts fuel consumption. 

---