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Measurement & Experimentation Laboratory ME301
Author:
Dr.Steve GibbsProfessor
The Saylor Foundation
USA
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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.
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This course will serve as your introduction to working in an engineering laboratory. You will learn to gather, analyze, interpret, and explain physical measurements for simple engineering systems in which only a few factors need be considered. This experience will be crucial to your success in analyzing more complicated systems in subsequent coursework and in the practice of mechanical engineering.
We frequently encounter measurement systems in our everyday lives.
Consider the following examples:
1. The many gauges found on the control panel of a motor vehicle indicate vehicle speed, engine coolant temperature, transmission setting, cabin temperature, engine speed, and oil pressureamongst many other measurements.
2. A routine visit to a physician often entails several measurements of varying complexityinternal temperature, blood pressure, internal appearance, heart rate, respiration rate, and tissue texture, amongst many, many more.
3. The experienced cook may use several measurements to successfully cook until donefor example, he or she might measure internal temperature, external coloration, external temperature and exposure time, internal coloration, aroma, and texture.
Question: A filter is an AC circuit that separates signals based upon ______
Choices:
Amplitude
Voltage
Frequency
Time
Duration
Question: A simple way to filter out low frequencies is to place _______
Choices:
An inductor in series with the load
A capacitor in parallel with the load
A capacitor in series with the load
A rapid switch in series with the load
None except this
Question: AC amplitude may be measured by_________
Choices:
Frequency
Period
Frequency and period
Duration
Peak-to-peak, RMS, or average amplitude
Question: A 6dB attenuator and a 50dB attenuator in series provide a total attenuation of
Choices:
300dB
56dB
5.4dB
50dB
None except this
Question: A signal (in the context of this course) is______
Choices:
An indication to start or stop an activity
An unexpected event
An electrical current
A detectable quantity used to communicate information
None except this
Question: Aliasing in signal digitization occurs when________
Choices:
A signal is digitized too rapidly
A signal is not digitized rapidly enough
A signal is not digitized with enough amplitude resolution
A connection is mislabeled
All including this
Question: A digital signal __________
Choices:
Is represented by numbers ranging from 1 to 10
Corresponds to the output of digital-to-analog converter
Is represented by 10 bits of data
Takes on discrete values over a range
None of the above
Question: A 12 bit ADC may have _____ unique output conditions.
Choices:
2[sup]11[/sup]
2[sup]10[/sup]
12[sup]2[/sup]
12[sup]10[/sup]
2[sup]12[/sup]
Question: Alternating current ________
Choices:
Oscillates at 60 Hz
Changes amplitude with time
Is always positive
Decays with time
None except this
Question: A power gain of 30 dB corresponds to a factor of _______
Choices:
10
30
100
1000
3000
Question: A current source __________
Choices:
Can supply an infinite current upon demand.
Supplies a constant current regardless of voltage within practical limits
Is the source in use at the present
Can supply AC or DC upon demand
Supplies current varying linearly with the output voltage