Metin Atmaca 030080007 3rd week definitions

1. Recycling (Savings – Environment):

Previous Definition (Better):

Once a waste is eventually generated, there are two basic options recycling and disposal. Recycling represents actions that manage in a way that results in using the
materials making the waste as feed stocks for some product or an application distinct
from disposal. This is done by segregating waste at source or by extracting materials
from it by various techniques, physical, chemical, thermal or biological.


(Resource recovery and recycling from metallurgical wastes Rao, S. Ramachandra Amsterdam ; London : Elsevier, 2006 PG.1)

New Definition:

Recycling of plastic materials is now an important field in the plastics industry, not just an activity born under environmental pressure. The recycling processes include industrial operations in which secondary materials are reprocessed and/or monomers recovered for further polymerization; such processes are termed secondary and tertiary recycling.

Although the plastics industry considered recycling for many years, attention was mainly focused on the recycling of industrial scraps and homogeneous post-consumer plastics which are easy to collect and reprocess. More recently, the plastics industry accepted the challenge of recycling of heterogeneous plastic waste based on new technologies of separation and reprocessing.

(Francesco Paolo La Mantia, Recycling of Plastic Materials, preface)


Fixed Definition:

The process of recycling requires that the owner of the waste material first separate out the useful items so that they can be collected separately from the rest of the solid waste. Many of the components of municipal solid waste can be recycled for remanufacturing and subsequent use, the most important being paper, steel, aluminum, plastic, glass, and yard waste. In 2008, about one-third of municipal solid waste was recycled. By recycling and composting, greenhouse gas emissions were reduced by an amount equivalent to the annual greenhouse gas emissions from 33 million passenger vehicles.

Theoretically, vast amounts of materials can be recycled from refuse, but this is not an easy task regardless of how it is approached. In recycling, a person about to discard an item must first identify it by some characteristics and then manually segregate it into a separate bin. The separation relies on some readily identifiable characteristic or property of the specific material that distinguishes it from all others. This characteristic is known as a code, and this code is used to separate the material from the rest of the mixed refuse using a switch.

In recycling, the code may be simple and visual. Anyone can distinguish newspapers from aluminum cans. But sometimes confusion can occur, such as identifying aluminum cans from steel cans, for example, or newsprint from glossy magazines, especially if the glossy magazines are intermingled with the Sunday paper.

Taking into account transportation and processing charges, it still appears that the economics for curbside recycling and materials recovery facilities in metropolitan areas (close proximity to refuse and markets) are quite favorable. The proof of this, of course, is the impressive number of materials recovery facilities (MRFs) in operation or under construction. According to the EPA, in 2008 about 146 million people were served by almost 9000 curbside recycling programs and 3500 community composting programs. In other words, more people recycle than vote. The success of recycling programs has been in spite of the severe obstacles that our present economic system places on the use of secondary materials. Some of these obstacles are identified here:

Location of wastes. The transportation costs of the waste may prohibit the implementation of recycling and recovery. Secondary materials have to be shipped to market, and if the source is too far away, the cost of the transport can be prohibitive.

Low value of material. The reason that an item is considered waste is that the material (even when pure) has little value. For example, the price paid for secondary polystyrene has fluctuated from a positive payment of $100 per ton to a negative payment of $300 per ton.

Uncertainty of supply. The production of solid waste depends on the willingness of collectors to transport it, the cooperation of consumers to throw things away according to a predictable pattern, and the economics of marketing and product substitution, which may significantly influence the availability of a material. Conversion from aluminum to plastic beverage containers—whether by legislation, marketing options, or consumer preferences—will significantly change the available aluminum in solid waste. The replacement of a high-value material (aluminum) by a low-value material (plastic) will adversely affect recycling. Potential solid waste processors thus have little control over their raw materials.

Administrative and institutional constraints. Some communities are unwilling to pay the additional cost to implement curbside recycling programs. The costs of these programs typically are in the $1 to $4 per month per household range. Other cities may have labor or contractual restrictions preventing the implementation of resource recovery projects. For example, many yard waste composting facilities are prohibited by land-use ordinances from accepting sludge or food waste, both of which may increase the value of the compost.

Legal restrictions. Some cities, such as San Diego, are prohibited from charging their residents for solid waste service, thus making it difficult to fund the implement of curbside recycling.

Uncertain markets. Recovery facilities must depend on the willingness of customers to purchase the end products—materials or energy. Often such markets are fickle, being either small, fragile operations or large, vertically integrated corporations that purchase the products on margin so as to satisfy unusually heavy short-duration demand.

(Worrell, W.A., Vesilind, P.A., Solid Waste Engineering, p.15)

2. Automatic Identification Systems (AIS) (Automation):

Previous Definition:

A guide to the collision avoidance rules: International Regulations for Preventing Collisions at Sea

(The definition was deleted)

New Definition (Better):

Auto-ID establishes electronic codes for products (e.g. EPC that can be compared to UPC/EAN). Furthermore, it introduces a standard for tags as well as for reading devices which should be efficient and cheap (which means that a basic reading device should not exceed the price of around €10). Object Naming Service (OMS), a language used for the description of products based on XML (a product markup language), and an infrastructure of programs called Savant are also part of the association’s efforts. Auto-ID develops certain standards for the identification process of objects which ensure that this kind of network will not depend on a standard introduced by a company producing RFID tags. Last but not least, the association is creating the infrastructure needed to allow the processing of the flow of information. (1)

(2)

( 1. Jean-Baptiste Walner, Nanocomputers and Swarm Intelligence, p. 210

  2. Auto ID Center, The New Network)

3. Jet blast cleaning (Repair in Manufacture):

Previous Definition:

One method of avoiding the physical impact between components that occurs in tumbling and barrel finishing is to strike the surface to be cleaned with a suitable fluid, the most commonly used being compressed air containing either steel shot or coarse sand. To isolate the jet cleaning operation from the surrounding environment, it is usually carried out in anenclosed cabinet. The component to be cleaned is loaded into the working area of the jet blaster cabinet and the stream of fluid is then directed either manually at the dirty surfaces or, less commonly, the workpiece is moved around under one or more fixed jets. Manual manipulation of either the jet nozzle or component is carried out through a rubber glove box. The spent shot, sand, etc. falls through a hole in the floor of the working area and is then recirculated.The compressed air used in jet blasting is at a pressure of up to 6 bar, which is conveniently the typical pressure found in most factory piped air supplies. Much lower pressures are used for non-ferrous parts. Jet blasting enables the impact fluid to be efficiently directed at internal surfaces, although it is alwaysdifficult to clean complex internally cored holes completely or, more importantly, to know whether or not theyhave been properly cleaned. An advantage of jet blasting is that the surface finish achieved provides a particularly good key for subsequent painting operations.Special portable units that invariably use water combined with chemical cleaning agents are frequently used to remove atmospheric contamination from the outside of buildings 

(Waters F., Fundamentals of Manufacturing for Engineers, p. 143).

New Definition (Better):

In accordance with an illustrative embodiment of the present invention disclosed herein, a liquid propelled blast nozzle apparatus includes a body having first and second bores which receive, respectively, a pressurized flow of sand particles and a high pressure and high velocity flow of propulsion fluid, a nozzle assembly on the body having a third bore for directing a blast of liquid propelled sand particles onto a surface to be cleaned, the respective bores defining axes which intersect one another within the bore of the nozzle assembly, the axis of the first bore intersecting the axis of the third bore at an angle of about 3^o , and the axis of the firs bore intersecting the axis of the second bore at an angle of about 7^o. The first and third bores preferably are lined with a suitable wear and erosion resistant material such as tungsten carbide.

This invention relates generally to blast nozzles used in cleaning metal surfaces with abrasive particles propelled by a combination of liquid and air, and particularly to a new and improved blast nozzle apparatus having a particular angular relationship between the axes of the abrasive particle and propulsion fluid inlets and the axis of the blast stream outlet that minimizes wear due to erosion to thereby provide a combination of a propulsion chamber and a nozzle with a service life that is substantially increased with respect to prior devices.

(J.P. Woodson, Wet Jet Blast Cleaning)

4. Wire Brushing (Mechanical Surface Cleaning Method):

Previous Definition:

Mechanical cleaning may be accomplish methods such as abrasive blast cleaning, wire brushing, grinding, tumbling, stream cleaning, or hot water cleaning.

Accesible surfaces may be wire brushed. Welds may be ground and wire brushed to remove slag, grit, or excess weld material. Carbon steel wire brushes must not be used on aluminum or stainless steel surfaces. Any wire brushes previously used on carbon steel can not be used on aluminum or stainless steel surfaces.

(Compressed Gas Association, Handbook Of Compressed Gas, pp. 202-207)

New Definition (Better):

One of the most familiar surface cleaning methods for removing contaminants such as surface scale and rust is the use of a stiff wire brush. It is cheap, easy to use and, while not providing a clean metal finish, is adequate for many non-critical applications. In most cases it is the preliminary step to subsequent operations, the most common of which is painting.

Power-driven rotary brushes are also available and are more suitable than hand brushes for larger jobs.

Advantages:

• -       Equipment simple, reliable and does not require skilled labour.

Disadvatages:

• -       Can be a dirty, noisy job
• -       Some parts too delicate to be cleaned by wire brushing.

(Fred Waters, Fundamentals of Manufacturing for Engineers, p.146)