Saturday, March 9, 2013

PROFESSIOAL PRACTICE

Profession

A profession is a vocation[the particular occupation for which you are trained or a group of persons associated by some common tie or occupation and regarded as an entity] founded upon specialized educational training, the purpose of which is to supply objective counsel[The act of exchanging opinions and ideas; consultation.] and service to others, for a direct and definite compensation, wholly apart from expectation of other business gain.


History

Classically, there were only three : divinity, medicine, and law[2]—the so-called "learned professions." The main milestones which mark an occupation being identified as a profession are:
  1. It became a full-time occupation;
  2. The first training school was established;
  3. The first university school was established;
  4. The first local association was established;
  5. The first national association was established;
  6. The codes of professional ethics were introduced;
  7. State licensing laws were established.
With the rise of technology and occupational specialization in the 19th century, other bodies began to claim professional status: architecture, pharmacy, veterinary medicine, nursing, teaching, librarianship, optometry and social work, all of which could claim, using these milestones, to be professions by 1900.
Just as some professions rise in status and power through various stages, so others may decline. This is characterized by the red cloaks of bishops giving way to the black cloaks of lawyers and then to the white cloaks of doctors.[clarification needed] More recently formalized disciplines, such as architecture, now have equally long periods of study associated with them.
Although professions enjoy high status and public prestige, not all professionals earn high salaries, and even within specific professions there exist significant inequalities of compensation; for example, a trial lawyer specializing in tort litigation on a contingent-fee basis may earn several times what a prosecutor or public defender earns.

List of professions

Professions include:










Formation of a profession

A profession arises when any trade or occupation transforms itself through "the development of formal qualifications based upon education, apprenticeship[Is the phenomenon whereby one is bound by legal agreement to learn a trade or occupation for another for a specific amount of time in return for instruction in a trade, art, or business, especially as a member of a labor union.], and examinations, the emergence of regulatory bodies with powers to admit and discipline members, and some degree of monopoly rights."

Regulation

Professions are typically regulated by statute[A law enacted by a legislature.], with the responsibilities of enforcement delegated[A person authorized to act as representative for another; a deputy or an agent.] to respective professional bodies, whose function is to define, promote, oversee, support and regulate the affairs of its members. These bodies are responsible for the licensure[The act or an instance of granting a license, usually to practice a profession] of professionals, and may additionally set examinations of competence and enforce adherence to an ethical code of practice. However, they all require that the individual hold at least a first professional degree before licensure.
Typically, individuals are required by law to be qualified by a local professional body before they are permitted to practice in that profession. However, in some countries, individuals may not be required by law to be qualified by such a professional body in order to practice, as is the case for accountancy in the United Kingdom (except for auditing and insolvency work which legally require qualification by a professional body). In such cases, qualification by the professional bodies is effectively still considered a prerequisite to practice as most employers and clients stipulate that the individual hold such qualifications before hiring their services.

Autonomy

Professions tend to be autonomous, which means they have a high degree of control of their own affairs: "professionals are autonomous insofar as they can make independent judgments about their work".This usually means "the freedom to exercise their professional judgement."
However, it has other meanings. "Professional autonomy is often described as a claim of professionals that has to serve primarily their own interests...this professional autonomy can only be maintained if members of the profession subject their activities and decisions to a critical evaluation by other members of the profession "The concept of autonomy can therefore be seen to embrace[An act of holding close with the arms, usually as an expression of affection; a hug.] not only judgement, but also self-interest and a continuous process of critical evaluation of ethics[A set of principles of right conduct.] and procedures from within the profession itself.
One major implication of professional autonomy is the traditional ban on corporate practice of the professions, especially accounting, architecture, medicine, and law. This means that in many jurisdictions[Authority or control], these professionals cannot do business through regular for-profit corporations and raise capital rapidly through initial public offerings. Instead, they must form special business entities such as limited liability[an obligation, responsibility, or debt] partnerships or professional corporations, which feature (1) reduced protection against liability for professional negligence and (2) severe limitations or outright prohibitions on ownership by nonprofessionals. In other words, all equity owners of the professional business entity must be professionals themselves. This avoids the possibility of a nonprofessional owner of the firm telling a professional how to do his or her job and thereby protects professional autonomy. But because professional business entities are effectively locked out of the stock market, they tend to grow relatively slowly compared to public corporations.

Status and prestige

Professions enjoy a high social status, regard and esteem[to have great respect or high regard for] conferred upon them by society. This high esteem arises primarily from the higher social function of their work, which is regarded as vital to society as a whole and thus of having a special and valuable nature. All professions involve technical, specialised and highly skilled work often referred to as "professional expertise." Training for this work involves obtaining degrees and professional qualifications without which entry to the profession is barred (occupational closure). Training also requires regular updating of skills through continuing education.

Power

All professions have power. This power is used to control its own members, and also its area of expertise[Skill or knowledge in a particular area.] and interests. A profession tends to dominate, police and protect its area of expertise and the conduct of its members, and exercises a dominating influence over its entire field which means that professions can act monopolist, rebuffing[A blunt or abrupt repulse or refusal, as to an offer.] competition from ancillary trades and occupations, as well as subordinating[Subject to the authority or control of another.] and controlling lesser but related trades.A profession is characterized by the power and high prestige it has in society as a whole. It is the power, prestige and value that society confers upon a profession that more clearly defines it. The power of professions has led to them being referred to as conspiracies against the laity[All those persons who are not members of a given profession or other specialized field.]. On the other hand, professionals acquire some of their power and authority in organizations from their expertise and knowledge. As such they can;-
  • bend rules
  • reduce bureaucratic inertia and
  • increase problem solving and adaptability.

Characteristics of a profession

There is considerable agreement about defining the characteristic features of a profession. They have a;-
  • professional association
  • cognitive base
  • institutionalized training
  • licensing
  • work autonomy
  • colleague control... (and)
  • code of ethics

Other meaning of professional

Professions are occupations with special power and prestige and that they comprise an exclusive elite group in all societies.
Members of a profession have also been defined as "workers whose qualities of detachment, autonomy, and group allegiance are more extensive than those found among other groups...their attributes include;-
  • a high degree of systematic knowledge
  • strong community orientation
  • loyalty
  • self-regulation
  • a defined system of rewards
  • administered by the community of workers.



A profession has been further defined as: "a special type of occupation...(possessing) corporate solidarity...prolonged specialized training in a body of abstract knowledge, and a collectivity or service orientation...a vocational sub-culture which comprises implicit codes of behaviour, generates an esprit de corps among members of the same profession, and ensures them certain occupational advantages...(also) bureaucratic structures and monopolistic privileges to perform certain types of work...professional literature, legislation, etc."

Tuesday, November 13, 2012


  

 
 
EXTRACTION OF IRON
 
 
 
INTRODUCTION
 
 Iron is extracted from its oxideore called HAEMATITE (Fe2O3).
 
PRINCIPLE OF EXTRACTION
 
 Extraction of iron is based on the reduction of HAEMATITE (Fe2O3) with carbon..
 
DETAILS OF EXTRACTION
 
 The process of the extraction of iron is carried out by the following steps:
  Concentration of ore
 Calcination or Roasting of ore
 Reduction of ore
 Concentration of ore:
In this metallurgical operation, the ore is concentrated by removing impurities like soil etc. The
process involves the crushing and washing of ore.
 Calcination or Roasting of ore:
The concentrated ore is now heated in the presence of air. The process of roasting is performed to remove moisture, CO2, impurities of sulphur, arsenic. Ferrous oxide is also oxidized to ferric oxide.
 
Reduction of ore
 
 The process of reduction is carried out in a blast furnace.
Blast Furnace
 
The blast furnace is a cylindrical tower like structure about 25m to 35m high. It has an outer shell of steel. Inside of furnace is lined with fire bricks. The top of the furnace is closed by a cup-cone feeder.
 
The charge
 
 The charge consists of :
roasted ore
Coke
Limestone
 
Details of reduction
 
 The charge is fed into the furnace from its top. A preheated blast of air at 1500OC, is blown into the furnace under pressure near to the bottom. The blast oxidizes carbon to CO2.
 
C + O2  CO2 + heat
Formation of CO2 is an exothermic reaction in which a huge amount of heat is liberated which rises the temperature to 1900OC in this region. As the CO2 passes upwards, it reacts more coke to form carbon monoxide.
CO2 + C  2CO + heat
Formation of CO is an endothermic reaction and the temperature in this region falls to 1100OC. CO
is the main reducing agent in the upper portion of blast furnace.
Reactions in blast furnace 
 
Fe2O+ 3C  2Fe + 3CO
Fe3O+ 4CO  3Fe + 4CO2 

CO2 + C  2CO     
Overall reaction
 
Fe2O+ 3CO  2Fe + 3CO2
The liquid iron runs downward to the bottom of the furnace and is withdrawn through tap hole.
Slag formation
 
Lime stone on heating decomposes to CaO and CO2.
CaCO3  CaO + CO2
CaO now reacts the impurities of ore called GANGUE to form slag. Slag is the mixture of CaSiO3
and Ca(AlO2)2. The slag floats over the top of molten iron. Slag is a useful byproduct. It is used
in road making, cement manufacturing a light weight building materials.
Flux + Gangue  Slag           
CaO + SiO2  CaSiO3
    CaO + Al2O3  Ca(AlO2)2
 
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BUILDING MATERIALS

METAL AND ITS PROPERTIES




                 
PROPERTIES OF METALS
This section is devoted primarily to the terms used in describing various properties and characteristics of metals in general. Of primary concern in aircraft maintenance are such general properties of metals and their alloys as hardness, brittleness, malleability, ductility, elasticity, toughness, density, fusibility, conductivity, and contraction and expansion. You must know the definition of the terms included here because they form the basis for further discussion of aircraft metals.

Hardness

Hardness refers to the ability of a metal to resist abrasion, penetration, cutting action, or permanent distortion. Hardness may be increased by working the metal and, in the case of steel and certain titanium and aluminum alloys, by heat treatment and cold-working (discussed later). Structural parts are often formed from metals in their soft state and then heat treated to harden them so that the finished shape will be retained. Hardness and strength are closely associated properties of all metals.

Brittleness

Brittleness is the property of a metal that allows little bending or deformation without shattering. In other words, a brittle metal is apt to break or crack without change of shape. Because structural metals are often subjected to shock loads, brittleness is not a very desirable property. Cast iron, cast aluminum, and very hard steel are brittle metals.

Malleability

A metal that can be hammered, rolled, or pressed into various shapes without cracking or breaking or other detrimental effects is said to be malleable. This property is necessary in sheet metal that is to be worked into curved shapes such as cowlings, fairings, and wing tips. Copper is one example of a malleable metal.


Ductility

Ductility is the property of a metal that permits it to be permanently drawn, bent, or twisted into various shapes without breaking. This property is essential for metals used in making wire and tubing. Ductile metals are greatly preferred for aircraft use because of their ease of forming and resistance to failure under shock loads. For this reason, aluminum alloys are used for cowl rings, fuselage and wing skin, and formed or extruded parts, such as ribs, spars, and bulkheads. Chrome-molybdenum steel is also easily formed into desired shapes. Ductility is similar to malleability.

Elasticity

Elasticity is that property that enables a metal to return to its original shape when the force that causes the change of shape is removed. This property is extremely valuable, because it would be highly undesirable to have a part permanently distorted after an applied load was removed. Each metal has a point known as the elastic limit, beyond which it cannot be loaded without causing permanent distortion. When metal is loaded beyond its elastic limit and permanent distortion does result, it is referred to as strained. In aircraft construction, members and parts are so designed that the maximum loads to which they are subjected will never stress them beyond their elastic limit.

NOTE: Stress is the internal resistance of any metal to distortion.

Toughness

A material that possesses toughness will withstand tearing or shearing and may be stretched or otherwise deformed without breaking. Toughness is a desirable property in aircraft metals.

Density

Density is the weight of a unit volume of a material. In aircraft work, the actual weight of a material per cubic inch is preferred, since this figure can be used in determining the weight of a part before actual manufacture. Density is an important consideration when choosing a material to be used in the design of a part and still maintain the proper weight and balance of the aircraft.

Fusibility

Fusibility is defined as the ability of a metal to become liquid by the application of heat. Metals are fused in welding. Steels fuse at approximately 2,500°F, and aluminum alloys at approximately 1, 110°F.

Conductivity

Conductivity is the property that enables a metal to carry heat or electricity. The heat conductivity of a metal is especially important in welding, because it governs the amount of heat that will be required for proper fusion. Conductivity of the metal, to a certain extent, determines the type of jig to be used to control expansion and contraction. In aircraft, electrical conductivity must also be considered in conjunction with bonding, which is used to eliminate radio interference. Metals vary in their capacity to conduct heat. Copper, for instance, has a relatively high rate of heat conductivity and is a good electrical conductor.