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2.1 Software development process Read Online
2.2 Requirements analysis Read Online
2.3 Software design Read Online
2.4 Software construction Read Online
2.5 Software testing Read Online
2.6 Software maintenance Read Online
2.7 Software configuration management Read Online
Virtually all countries now depend on complex computer-based systems. More and more products incorporate computers and controlling software in some form. The software in these systems represents a large and increasing proportion of the total system costs. Therefore, producing software in a cost-effective way is essential for the functioning of national and international economies.
Software engineering is an engineering discipline whose goal is the cost-effective development of software systems. Software is abstract and intangible. It is not constrained by materials, governed by physical laws or by manufacturing processes. In some ways, this simplifies software engineering as there are no physical limitations on the potential of software. In other ways, however, this lack of natural constraints means that software can easily become extremely complex and hence very difficult to understand.
Software engineering is still a relatively young discipline. The notion of ‘software engineering’ was first proposed in 1968 at a conference held to discuss what was then called the ‘software crisis’. This software crisis resulted directly from the introduction of powerful, third generation computer hardware. Their power made hitherto unrealisable computer applications a feasible proposition. The resulting software was orders of magnitude larger and more complex than previous software systems.
Early experience in building these systems showed that an informal approach to software development was not good enough. Major projects were sometimes years late. They cost much more than originally predicted, were unreliable, difficult to maintain and performed poorly. Software development was in crisis. Hardware costs were tumbling whilst software costs were rising rapidly. New techniques and methods were needed to control the complexity inherent in large software systems.
These techniques have become part of software engineering and are now widely although not universally used. However, there are still problems in producing complex software which meets user expectations, is delivered on time and to budget. Many software projects still have problems and this has led to some commentators (Pressman, 1997) suggesting that software engineering is in a state of chronic affliction.
As our ability to produce software has increased so too has the complexity of the software systems required. New technologies resulting from the convergence of computers and communication systems place new demands on software engineers. For this reason and because many companies do not apply software engineering techniques effectively, we still have problems. Things are not as bad as the doomsayers suggest but there is clearly room for improvement.
Question: Arc -flash protective clothing and equipment are rated to:
Choices:
Provide protection to the value indicated as the “arc rating” or “ATPV”
Provide a 50% probability of a burn at the arc rating or ATPV
Provide protection in excess of the arc rating or ATPV
Allow a person to safely work on an energized electrical power system
Question: At what voltage does the arc flash hazard not exist?
Choices:
480 volts
277 volts
208 volts
None of the above
Question: What are the insulation power-factor tests typically performed on a medium-voltage, air-magnetic circuit breaker?
Choices:
Six guarded-specimen tests and three ungrounded-specimen tests
Three ungrounded-specimen tests and six grounded-specimen tests
Three guarded-specimen tests and six grounded-specimen tests
Six ungrounded-specimen tests and three guarded-specimen tests
Question: When evaluating insulation-resistance test results on a medium-voltage, air-magnetic circuit breaker, what quantity is evaluated?
Choices:
Percent power factor
Capacitance
Insulation watts-loss
Megohms
Question: When is the danger of an arc flash the greatest for draw-out circuit breakers?
Choices:
When opening the circuit breaker
When closing the circuit breaker
When racking the circuit breaker in
When racking the circuit breaker out
Both C and D
Question: When wearing an arc-rated face shield, what is the correct body position when operating electrical equipment?
Choices:
Extend the left arm and turn the face away from the hazard
Extend the right arm and turn the face away from the hazard
Extend either arm and turn your face towards the hazard
Get an apprentice to do it for you
Question: Electrical systems rated less than 240 volts fed by a transformer with a capacity of <125 kVA are not considered an arc-flash hazard.
Choices:
True, according to IEEE 1584
False
Question: Which of the following is NOT a rule-of thumb concerning arc flash:
Choices:
Incident energy decreases by the inverse square of the distance
Incident energy is proportional to time
Each layer of clothing under arc-rated reduces the heat to the body by ~ 50%
Incident energy is inversely proportional to short circuit current
Question: What electrical test can help determine the condition of the contact pivot’s lubrication state?
Choices:
Insulation power factor
Contact resistance
Insulation resistance
Vacuum bottle integrity test
DC overpotential
Question: Which OSHA regulation requires a hazard/risk analysis of the workplace?
Choices:
1910.132
1926.222
1910.335
1910.147
Question: What dangerous energy could be released during a vacuum bottle integrity test?
Choices:
Gamma rays
Nuclear radiation
X-rays
None
Both A and C