3. .ibration analysis: This includes an on-line analysis of the vibrationsignals， FFT spectral analysis， transient analysis， and diagnostics. Awide variety of displays are available includingorbits， cascades， bodeand nyquistplots， and transient plots.
4. Mechanical analysis: This includes detailed analysis of the bearing tem-peratures， lube， and seal oil systems and other mechanical subsystems.
5. Corrosion analysis: .n-line electrochemical sensors are being used to monitor changes in the corrosivity of flue gases especially in exhaust stacks. The progressive introduction of ever-more stringent regula-tions to reduce ..x emissions has resulted in an increase in the risk of water wall tube wastage in large powerboilers， refinery process heaters and municipal waste incinerators.
6. Diagnosis: This includes several levels of machinery diagnosis assist-ance available via expert systems. These systems must integrate both mechanical and aerothermal diagnostics.
7. Trending and prognosis: This includes sophisticated trending and prognostic software. These programs must clearly provide users to clearly understand underlying causes of operating problems.
8. ""What-i '' analysis: This program should allow the user to do various studies of plant operating scenarios to ascertain the expected perform-ance level of the plant due to environmental and other operational conditions.
.onitoringSoftware
The monitoring software for every system will be different. However， allsoftware is there to achieve one goal.it must gather data， ensure that it iscorrect， and then analyze and diagnose the data. Presentations must be in a convenient form and should be easily understood by plant operational person-nel. All priorities must be to the data collection process. This process must not in any manner be hampered since it is the corner stone of the whole system.
A convenient ramework within which to categorize the software could be as follows:
1. Graphic User Inter ace (GUI).This consists of screens， which would enable the operator to easily interrogate the system and to visually see where the instruments are installed and their values at any point oftime. By carefully designed screens， the operator will be able to view ata glance the relative positions of all values，thus， fully understanding the operation of the machinery.
2. Alarmjsystem logs.To fully understand a machine we have to have various types of alarms. The following are some of the suggested types of alarms:
a. Instrument alarms: These alarms are based on the instrumentation range.
b. .alue range alarm: These alarms are based on operating values of individual points both measured and calculated points. These alarms should be variable in that they would change with operat-ing conditions.
c. .ate o change alarm: These alarms must be based on any rapid change in values in a given time range. This type of alarm is very useful to detect bearingproblems， surgeproblems， and other instabilities.
d. .rognostic alarms: These alarms must be based on trends and the prognostics based on those trends. It is advisable not to haveprognostics， which project in time more than the time of data that is trended.
3. .er ormance maps: These are performance maps based on design or initial tests (base lines) of the various machinery parameters. Thesemaps， for example present how power output varies with ambientconditions， orwith properties of thefuel， or the condition of the filtration system; or how close to the surge line a compressor isoperating. .n thesemaps， the present value is displayed， thus allow-ing the operator to determine the degradation in performance occur-ring in the units.
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