Dynamic Positioning Systems in Maritime Operations
Dynamically Controlled Vessels
These vessels are capable of maintaining position at sea without the use of moorings or anchors. This is achieved by using propulsion units called computer-controlled thrusters. It is common to see several tunnel thrusters side by side, either at the bow or stern. While tunnel thrusters are fixed, azimuth thrusters can rotate 360 degrees. All these vessels still retain their main thrusters and rudders.
Dynamic Positioning: Principles of Operation
Dynamic Positioning (
Read MoreUnderstanding Control Systems: Proportional, Integral, Derivative & More
Understanding Control Systems
Proportional Control
A proportional (P) control system responds to an error signal, providing a symmetrical correction proportional to the error. A constant error signal results in a constant corrective action. Sudden changes in the error signal lead to a fast response from the controller.
Proportional-Integral Control
In proportional-integral (PI) control, the error signal causes a growing response due to the integral action of the controller. This type of control is suitable
Read MoreUnderstanding Control Actions: Integral, Derivative, Proportional
Integral Action
Moves the valve at a rate proportional to the integral area obtained between the variation of the variable and the set point over time.
Time Integral Action
The interval of time during which, when a step input signal is applied, the output signal due to the integral action equals that due to the proportional action.
Reset Windup
This is the phenomenon that occurs when the error decreases while the area under the integral action continues to increase. This may lead to saturation of the
Read MoreTRIAC and GTO Thyristors: Operation and Advantages
TRIAC
- An SCR is a unidirectional device; it can conduct from anode to cathode only and not from cathode to anode.
A TRIAC can conduct in both directions.
TRIAC: Bidirectional thyristor with three terminals.
Extensively used for the control of power in AC circuits.
- A TRIAC is a bidirectional device, and its terminals can have various combinations of positive and negative voltages. There are four possible electrode potential combinations, as given below:
MT2 is positive with respect to MT1, G positive with
Read MoreComputer Architecture and Number Systems FAQ
Computer Architecture and Number Systems
Frequently Asked Questions
What does the abbreviation EBCDIC stand for?
Extended Binary Coded Decimal Interchange Code
How are floating-point numbers written in general form?
N = m * be (mantissa * baseexponent)
What is two’s complement notation and where is it used?
It is used in machines with very short word lengths, e.g., 8 bits. It incorporates the sign bit into the number.
What does the term SPEC stand for?
System Performance Evaluation Corporation
How does an
Read MoreSocial Networks and Web Evolution: 1.0 to 3.0
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