1-Bingham plastic (A form of plastic material)
(old definition) (better)
Bingham plastic fluids.The Bingham plastic theory assumes that a fluid has a rheology where the relationship between shear stress and shear rate is linear
but the line does not cross the origin of the graph.It looks something like the graph below in figure.
This type of rheology exhibits a yield point.Before the fluid will flow, a certain threshold pressure must be applied and any pressure lower than this will not initiate flow.When the fluid is static, a structure builds up which connects particles in the fluid due to electrostatic attractions between them and forms a gel. For a drilling fluid, this is desirable property because when circulation stops and a gel forms, drilled solids are suspended within the gel and do not sink down through the mud. When sufficient shear stress is applied the fluid starts to move and gel structure breaks down again.The slope of the graph(which a straightline in the mathematical model) is given the term 'plastic viscosity'.Therefore to define the behaviour of a Bingham plastic type fluid,the yield point and plastic viscosity are sufficient to predict the shear stress for a given shear rate.
(Steve Devereux,Drilling for oil & gas: a nontechnical guide,p.157)
(new definition)
Bingham plastic materials have a distinguishing feature a yield stress is present. Once flow is established, the relationship between shear stress and shear rate is linear, explaning why n=1.0 and K is a constant value known as the plastic viscosity. Caution, the plastic value is not the same as apparent viscosity or the Newtonian viscosity.
(Editor: Suzanne NIELSEN, Food Analysis,pg:547)
2- Normalizing (A thermal operation)
(old definition) (better)
Normalizing. Heating a ferrous alloy to a suitable temperature above the transformation range (and typically above the suitable hardening temperature) and then cooling in air to a temperaturesubstantially below the transformation range.
Normalizing is a process that involves heating the part above the upper critical temperature and then air cooling outside the furnace to relieve residual stresses and for dimensional stability (Fig. 18.16). Normalizing is often considered from both a thermal and microstructural standpoint. In the thermal sense, normalizing is austenitizing followed by cooling in still or slightly agitated air or nitrogen. In a microstructural sense, the areas of the microstructure that contain about 0.8% carbon are pearlitic; while the areas of low carbon are ferritic. A normalized part is very machinable but harder than an annealed part. Good normalizing practice requires:
• The part be uniformly heated to a temperature high enough to cause complete transformation to austenite.
• The part remain at temperature long enough to achieve uniform temperature throughout the section size.
• The part be allowed to cool uniformly in still air to room temperature.
(Hwaiyu Geng, Manufacturing Engineering Handbook, McGrawHill, page 346 Unit 18.6)
(new definition)
This process is often considered from both thermal and microstructural standpoints. In the Thermal sense normalizing is an austenitizing heating cycle, followed by cooling in still or agitated air. Typical normalizing temperatures for many standart steels are given in an accompanying Table.
In terms of microstructure, areas that contain about 0.8% are pearlitic. those low in carbon are ferritic.
All standart, low-carbon, medium-carbon, and high carbon wrought steels can be normalized as well as many steels castings.Many weldmends are normalized to refine the structure within the weld-affected zone, and maraging steels either can't be normalized. or are not usualy normalized.
(Editör: Harry Chandler, Heat treater's guide: practices and procedures for irons and steels, pg:28)
3-Phosphate coatings: (Surface treatment)
(Old definition) (better)
Phosphate coatings are formed by immersing metals (usually steel or zinc) in baths where metal phosphates (iron, zinc, and manganese phosphates are all common) have been dissolved in solutions of phosphoric acid. The resultant coatings can be used to precondition surfaces to receive and retain paint or enhance the subsequent bonding with rubber or plastic. In addition, phosphate coatings are usually rough and can provide an excellent surface for holding oils and lubricants. This feature can be used in manufacturing, where the coating holds the lubricants that assist in forming, or in the finished product, as with black-color bolts and fasteners, whose corrosion resistance is provided by a phosphate layer impregnated with wax or oil.
(MATERIALS AND PROCESSES IN MANUFACTURING 10th edition, J. Temple Black, Ernest Paul DeGarmo, Ronald A. Kohser, p.953)
(new definition)
Phosphating process can be defined as the treatment of a metal surface so as to give a reasonably hard, electrically non-conducting surface coating of insoluble phosphate which is contiguous and highly adherent to the underlying metal and is consider- ably more absorptive than the metal [9]. The coating is formed as a result of a topochemical reaction, which causes the surface of the base metal to integrate itself as a part of the corrosion resistant film.
(T.S.N. Sankara Narayanan, Surface Pretreatment by Phosphate Conversion Coatings, A Review, pg:131)
4-Object-Oriented Models (programming language)
An Object-Oriented(OO) model organizes a system around real-world objects, or conceptual objects, that exist in the user's world, as opposed to functions and data that are split apart. A real-world object, an entity that exists within the application domain, is defined in terms of its responsibilities (behavior), its data (attributes), and its relationships to other objects. All functions of the object are encapsulated (hidden) in the details of the object itself. Therefore, when functional changes are required, they are made within the object, causing little or no disruption to the rest of the model. To utilize the modified or added functions in an object, the remaining objects in the model can be provided with an interface.
The goal of a good object-oriented model is to have self-sufficient objects. This type of object is capable of initiating itself and possesses the intelligence to manage itself through several states, to provide its functional responsibility in the model.
(Quality Software Project Management, Robert T. Futrell; Donald F. Shafer; Linda I. Safer, Prentice Hall, 2002, chapter 22)
(new definition) (better)
Explosion welding (EXW), uses detonation of an explosive to accelerate a component, called a flyer, to high velocity as it collides with the other component being welded. At the moment of impact, the kinetic energy of the flyer plate is released as a compressive stress wave on the surfaces of the two components, forming a metallurgical bond. In this process the collision progresses across the surfaces of the plates being welded, forming an angle between the two colliding components, The surface films are liquefied, scarfed off the colliding surfaces, and jetted out of the interface leaving perfectly clean, oxide-free surfaces. Under these conditions the interaction within the molecules and atoms and the resultant forces create cohesion, and the resultant weld is without any HAZ.
As described above, the explosion provides the energy for the weld. so the detonation velocity should be within the limits to produce the required impact velocity and angle between the two components. The sonic velocity within the material being welded limits the expIosion velocity, This is a very important variable, because if the detonation velocity exceeds the metal sonic velocity, shock waves will be formed. Since these have sonic velocities, they travel faster than the detonation wave. causing spalling along the edges and fissuring at the weld interface. Controlling the amount of charge per unit area can alter the flyer-plate velocity, When high velocity explosives are used. the process will demand thick buffers between explosive and the cladding plate.
1. Larger waves are produced with same angle of incidence.
2. The range of angles within which waves are produced also increases.
3. The angle of incidence at which weld waviness occurs begins to increase.
4. There is increased tendency for the formation of intcrmemllic compounds
in the weld interface area
The correct amount of explosives should be used. Too little explosive will be unable to develop a velocity capable of welding. The explosives used arc varied, and include plastic flexible sheet. cord, pressed, cast, granulated and liquid, Standard commercial blasting caps achieve detonation, The detonation velocity tends to be constant throughout the explosion, The energy released by explosives is dependent on the thickness of the explosive spread and degree of confinement. These factors, along with the ingredients in the explosive used, become the variables controlling the detonation velocity.
(new definition) (better)
Object-Orientation is a set of tools and methods that enable software engineers to build reliable, user friendly, maintainable, well documented, reusable software systems that fulfills the requirements of its users. It is claimed that object-orientation provides software developers with new mind tools to use in solving a wide variety of problems. Object-orientation provides a new view of computation. A software system is seen as a community of objects that cooperate with with each other by passing messages in solving a problem.
An object-oriented programming laguage provides support for the following objectoriented concepts:
Objects and Classes
Inheritance
Polymophism and Dynamic binding
(School of Computer Science University of KwaZulu-Natal, Object-Oriented Programming, pg:11-12)
5-Explosion Welding (Manufacturing method-kind of welding)
(old definition)
Explosion welding (EXW) is a pressure-welding process that represents a special case. In explosion welding, the workpieces usually start out cold but heat significantly and extremely rapidly very locally at their faying surfaces during the production of the actual weld. The controlled detonation of a properly placed and shaped explosive charge causes the properly aligned workpieces to come together extremely rapidly at a low contact angle. When this occurs, air between the workpieces is squeezed out at supersonic velocities. The resulting jet cleans the surfaces of oxides and causes very localized but rapid heating to high temperatures.
(Wessler R.W., Principles of welding: processes, physics, chemistry, and metallurgy, 1999, p. 103)
(new definition) (better)
Explosion welding (EXW), uses detonation of an explosive to accelerate a component, called a flyer, to high velocity as it collides with the other component being welded. At the moment of impact, the kinetic energy of the flyer plate is released as a compressive stress wave on the surfaces of the two components, forming a metallurgical bond. In this process the collision progresses across the surfaces of the plates being welded, forming an angle between the two colliding components, The surface films are liquefied, scarfed off the colliding surfaces, and jetted out of the interface leaving perfectly clean, oxide-free surfaces. Under these conditions the interaction within the molecules and atoms and the resultant forces create cohesion, and the resultant weld is without any HAZ.
As described above, the explosion provides the energy for the weld. so the detonation velocity should be within the limits to produce the required impact velocity and angle between the two components. The sonic velocity within the material being welded limits the expIosion velocity, This is a very important variable, because if the detonation velocity exceeds the metal sonic velocity, shock waves will be formed. Since these have sonic velocities, they travel faster than the detonation wave. causing spalling along the edges and fissuring at the weld interface. Controlling the amount of charge per unit area can alter the flyer-plate velocity, When high velocity explosives are used. the process will demand thick buffers between explosive and the cladding plate.
1. Larger waves are produced with same angle of incidence.
2. The range of angles within which waves are produced also increases.
3. The angle of incidence at which weld waviness occurs begins to increase.
4. There is increased tendency for the formation of intcrmemllic compounds
in the weld interface area
The correct amount of explosives should be used. Too little explosive will be unable to develop a velocity capable of welding. The explosives used arc varied, and include plastic flexible sheet. cord, pressed, cast, granulated and liquid, Standard commercial blasting caps achieve detonation, The detonation velocity tends to be constant throughout the explosion, The energy released by explosives is dependent on the thickness of the explosive spread and degree of confinement. These factors, along with the ingredients in the explosive used, become the variables controlling the detonation velocity.
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