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WorksheetsQuiz 1 Control-Introduction to control and modelling
Total questions: 10
Worksheet time: 10mins
Process control in the process industry is primarily concerned with
A) Ensuring product quality, process safety, and compliance with environmental regulations.
B) Maximising production rate and profit while ignoring safety and environmental considerations.
C) Controlling only the temperature and pressure of a process and other parameters of the process
D) Studying the chemistry of materials without implementing automation.
In process control, which of the following statements correctly distinguishes between disturbances, manipulated variables, and output variables?
A) Disturbances (d or D) are variables deliberately adjusted by controllers to maintain output variables (y or Y) at set values.
B) Manipulated variables (u or U) are uncontrolled inputs that affect the process outputs randomly.
C) Output variables (y or Y) may be controlled or uncontrolled and are typically measured online, while manipulated variables (u or U) are adjusted by controllers to meet control objectives.
D) Disturbances (d or D) are output variables that are never measured and cannot affect the process.
Which of the following statements correctly describes an open loop control system?
A) The controller adjusts the process based on feedback from the output to correct any errors.
B) The system operates without feedback, relying on proper calibration and consistent external conditions; it is simple, cost-effective, and fast, but cannot correct errors or compensate for disturbances.
C) Open loop control is highly accurate even if external conditions change, because it constantly monitors the output.
D) It combines feedback and feedforward strategies to improve performance and reduce sensitivity to disturbances.
Which of the following statements best describes a feedback (closed loop) control system?
A) The system operates without measuring the output, relying only on pre-set commands to the actuator.
B) Feedback control anticipates disturbances and adjusts the manipulated variable before any deviation occurs.
C) The controlled variable is measured, and this measurement is used to adjust the manipulated variable; disturbances are not measured.
D) It ignores deviations in the output and cannot reduce the sensitivity to unmeasured disturbances.
In which one of the following options ALL are based on feedback control system?
A)
1. Room Heater / Air Conditioner (Thermostat)
2. Car Cruise Control
3. Water Tank Level Controller
B)
1. Electric Toaster
2. Microwave Oven (Time-Based)
3. Fixed-Time Traffic Signal
C)
1. Weather-Based Air Conditioning Control
2. Modern Car Engine Control (Acceleration)
3. Smart Oven with Preheating Control
D)
1. Room Heater / Air Conditioner (Thermostat)
2. Microwave Oven (Time-Based)
3. Fixed-Time Traffic Signal
Which of the following best describes the type of control strategy in which the disturbance variable is measured, but the controlled variable is not?
A. Feedback control, where corrective action is taken only after the controlled variable deviates from the set point and no process model is required.
B. Feedforward control, where corrective action is taken before the controlled variable deviates from the set point using a process model of the disturbance effect.
C. On–off control, where the controller switches fully on or off whenever the measured disturbance exceeds a fixed threshold.
D. Cascade control, where a primary controller sets the set point for a secondary controller that compensates for unmeasured disturbances.
Which of the following best describes a dynamic process model?
A. A model that assumes all variables remain constant with time and excludes accumulation terms.
B. A model in which variables change with time, includes accumulation terms, and time derivatives appear in the equations.
C. A purely empirical steady-state model used only for design at fixed operating conditions.
D. A model used only for economic optimisation, ignoring process safety, start-up, shutdown, and disturbances.
A chemical engineer is developing a model for a non-isothermal reactor in which an exothermic reaction occurs. The engineer writes differential mass and energy balances based on conservation laws and known kinetics, but several heat-transfer and kinetic parameters are unknown and are estimated by fitting the model to pilot-plant data. The final model is then used to predict reactor performance at conditions outside the experimental range.
A. It is a purely theoretical model, because it is based on conservation laws and kinetic expressions without relying on experimental information for parameter values.
B. It is a purely empirical model, because parameter estimation from pilot-plant data means the model structure itself is determined entirely by experiments.
C. It is a semi-empirical model, because a fundamental balance-based structure is combined with experimentally determined constants obtained from data fitting.
D. It cannot be classified using the given categories, because the use of both balances and data automatically invalidates the derivation-based classification.
According to this figure, if we write a model based on material balance, what type of equation finally will be obtained? what is the typical solution method?
A) Algebraic equation will be obtained and it can be solved by basic algebra
B) ODE will be obtained and it can be solved using analytical method
C) PDE will be obtained and it must be solved using numerical methods
D) ODE will be obtained and it can be solved using numerical method
Which one of the following options are showing feedforward control strategy?
A)
A)
B)
B)
C)
C)
D)
D)
