Overcoming Pollution
very efficiently transmitted through the generally stiff, metallic and therefore resonant structures. One common way of overcoming the considerable nuisance this can cause for the occupants is by absorbing the vibration and actually converting it to heat using viscoelastic polymer materials, typically based on polyurethanes or acrylics.
Over the past 20 years, Swedish Acoustic Products -- Swedac -- has built a track record in overcoming noise and vibration problems using this basic technology. Goran Falk, the company's technical director, claims it is possible to reduce noise levels by 50-70% with the right choice of materials and their effective application.
"Although we have a range of standard products, the skill comes in knowing how best to use them. One also has to keep an open mind about modifying existing products or designing completely new solutions when the conditions require it," he says. Falk believes that sound and vibration suppression should be an integral element of the design of the structure as a whole and not an 'add-on'. For this reason, Swedac offers sound-damping engineering consultancy to ship and offshore platform designers and builders.
The company has supplied over 200,000 m2 of sound-damping deck coverings over the past 15 years. These generally consist of a trowel-applied liquid polymer, which, when dry, is overlaid with an SBR latex concrete. If speed of application is an issue, the liquid-applied polymer can be replaced with an adhesively-bonded polymer sheet.
Where the requirements are more stringent, for example, in laboratory areas, the company can offer a 'floating floor'. This comprises proprietary sound-damping PVP (plate/viscoelastic polymer/plate) laminate plates laid on top of 50mm of mineral wool (140-150 Kg/m3). The sound-damping plates, which were conceived by Swedac, consist of two layers of steel or aluminium, each 2 or 3 mm thick, separated by a thin layer of viscoelastic polymer.
While the performance of this type of system is impressive, even better sound and vibration suppression can be achieved, particularly at the lower frequencies commonly produced by engines, propellers, mud pumps and so on, by combining the floating floor with the company's standard viscoelastic polymer plus SBR latex concrete system (Figure 1). The measured insertion loss, ILv, expressed in dB for this system over a range of frequencies is shown in Figure 2.
Emtunga modules
Swedac has developed similar but thinner (2 mm total) and lighter PVP laminate plates for attaching to bulkheads to reduce noise transmission between cabins.
The results collected during this investigation were as follows: 68.4 dB for the 10 cm pipe, 69.8 dB for the 20 cm pipe, 79 dB for the 30 cm pipe, 84.2 dB for the 40 cm pipe, and 84.2 dB for the 50 cm pipe. The hypothesis states: if the length of the PVC pipes were to increase and the frequency used in this experiment remained the same, then the sound produced from the pipe will have a lower amplitude each time. According
The protective packaging industry can be segmented three ways by use: positioning, block, and bracing; flexible wraps; and void fill. Coated (e.g., AirCap) and uncoated air bubble products serve the flexible wrap and void fill markets (refer to Glossary). The flexible wrap market, which dwarfs void fill as measured by annual sales, is of primary concern to Sealed Air and will thus constitute the focus of this report.
More than three million children under the age of five have passed away because of pollution and other environmental factors (Rinkesh). Pollution is the leading cause of death among developing countries (Petru, Alexis). Air pollution analyst and environmental chemist are two careers that focus on improving our environment to make it safer to live in.
The Avro Anson V has a molded plywood fuselage which was a key factor to its success in the Canadian climate. The fuselage of the plane was made of sheets of spruce and casein glue making it very lightweight compared to the metal alternatives. The fuselage was very aerodynamic and draft free which increased the vehicles performance. In order to manufacture a molded plywood fuselage three layers of spruce plywood strips are stacked and soaked with casein glue inside a concave mold. After the layers are completed a large rubber bladder is fastened to the top of the mold and inflated for a period of twenty-four hours. Once the bladder is removed one half shell is complete. Two shells can easily be joined together creating an extremely smooth fuselage for the aircraft.
Sounds play a vital role in parts of life, whether it be lovely or frustrating, it can lead one to commit serious conflicts.
designed for building structures. With these plastic blocks the company was able to market to all
Now when the advertisement is clearly analyzed it is evident that the advertisement stated false claims like it can be used in any type of sound delivery equipments and after scientific tests it has been proved that it improves the sound quality by 50 %. But when the product was put to actual use it was faulty and did not satisfy any of the things claimed in the advertisement.
Bachmann, H., & Steinle, A. (2011). Precast concrete structures / Hubert Bachmann, Alfred Steinle. Berlin: Ernst & Sohn, c2011.
A Roman architect named Marcus Pollio, who lived in the first century BC, was the first to study the acoustics of buildings. “He made some pertinent observations on the subject and some astute guesses concerning reverberation and interference”(Encarta). Reverberation and interference are two of the more important aspects of acoustical architecture. Both deal with the sound waves music or instruments make. By understanding reverberation, which is the echoing of sound waves, early architects could better construct buildings and auditoriums that would produce better acoustics. An architect has two types of material he can use to modify a building to deal with reverberation and the quality of sound. In many buildings such as meeting halls and auditoriums where echoes are not wanted, absorption materials such as cork and felt are used to absorb reverberations. On the other hand, in buildings such as concert halls and opera houses where reverberation is important reflecting material is used. Materials such as metal and most stones can be use to reflect sound waves to the audience. With these materials an architect can modify the way sound travels in his building.
Fingering and Acoustic Schematic. n.d. Diagram. University of New South Wales, Faculty of Science. Academic Press, 2001. Web. 13 Sept. 2011.
“Sound or acoustic energy involves the actual vibration of the actual material through which it passes and thus, in general, propagates best through solids and liquids, less well in gasses and not at all in a vacuum” (Wright et al., 1995, p. 70)
Engineers set up all building codes based on accurate calculations that are based on theories and actual observations known as seismic assessment. . There are two different types of seismic performance assessments, experimental assessment and numerical assessment. Experimental assessments are very expensive since engineers need to build a scaled m...
Efforts to improve the standard of living for humans--through the control of nature and the development of new products--have also resulted in the pollution, or contamination, of the environment. Much of the world's air, water, and land is now partially poisoned by chemical wastes. Some places have become uninhabitable. This pollution exposes people all around the globe to new risks from disease. Many species of plants and animals have become endangered or are now extinct. As a result of these developments, governments have passed laws to limit or reverse the threat of environmental pollution.
Charles and Keith uses synthetic materials and polyurethane to ensure affordable prices of their products (Singapore Press Holding, 2009). However, the qualities of the products are not compromised despite its inexpensive prices. The managing director Charles Wong reassured the customers that although the ...