Journal of colloid interface and science

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To avoid this situation, we design the control system by first setting up the range of possible errors and then designing the controller in Prazosin HCl (Minipress)- Multum a way that, if the error of the system stays within the assumed range, the designed control system will stay stable.

The design method based on this principle is called robust control theory. This theory incorporates both the frequencyresponse approach and the time-domain approach.

The theory is mathematically very complex. The reader interested in details of robust control theory should take a graduate-level control course at an established college or university. Journal of colloid interface and science we can discuss control systems, some basic terminologies must be defined. Controlled Variable and Control Signal or Manipulated Variable. Journal of colloid interface and science controlled variable is the quantity or condition that is measured and controlled.

The control signal or manipulated variable is the quantity or condition that is varied by the controller so as to affect the value of the controlled variable. Normally, the controlled variable is the output of the system. Control means measuring the value of the controlled variable of the system and applying the control signal to the system to correct or limit deviation of the measured value from a desired value. In studying control engineering, we need to define additional terms that are necessary to describe control systems.

In this book, we shall call any physical object to be controlled (such as a mechanical device, a heating furnace, a chemical reactor, or a spacecraft) a plant. In this book we shall call any operation to be controlled a process. Examples are chemical, economic, and biological processes.

A system is a combination of components that journal of colloid interface and science together and perform a certain objective. A system need not be physical. The concept of the system can be applied to abstract, dynamic phenomena such as those encountered in economics.

The word system should, therefore, be interpreted journal of colloid interface and science imply physical, biological, economic, and journal of colloid interface and science like, systems. A disturbance is a signal that tends to adversely affect the value of the output of a system. If a disturbance is generated within the system, it is called internal, while an external disturbance is generated outside the system and is an input.

Feedback control refers to an operation that, in the presence of disturbances, tends to reduce the difference between the output of a system and some reference input and does so on the basis of this difference.

Here only unpredictable disturbances are so specified, since predictable or known disturbances can always be compensated for within the system. The amount of fuel admitted to the engine is adjusted according to the difference between the desired and the actual engine speeds. The sequence of actions may be stated as follows: The speed governor is adjusted such that, at the desired speed, no pressured oil will flow into either side of the power cylinder.

If the actual speed drops below the desired value due to disturbance, then the decrease in the centrifugal force of the speed governor journal of colloid interface and science the control valve to move downward, supplying more fuel, and the speed of the engine increases until the desired value is reached.

On the other hand, if the speed of the engine increases above the desired value, then the increase in the centrifugal force of the governor causes the control valve to move upward. This decreases the supply of fuel, and the speed of the engine decreases until the desired value is reached. In this speed control system, the plant (controlled system) is the engine and the controlled variable is the speed of the engine.

The difference between the desired speed and the actual speed is the error signal. The control signal (the amount of fuel) to be applied to the plant (engine) is the actuating signal. The external input to disturb the controlled variable is the disturbance.

An unexpected change in the load is a disturbance. The temperature in the electric furnace is measured by a thermometer, which is an analog device. The digital temperature is fed to a controller through an interface. This digital temperature is compared with the programmed input temperature, and if there is any discrepancy (error), the controller sends out a signal to the heater, through an interface, amplifier, and relay, to bring the furnace temperature to a desired value.

Journal of colloid interface and science business system may consist of many groups. Each task assigned to a group will represent a dynamic element of the system. Feedback methods pro vera reporting the accomplishments of each group must be established in such a system for proper operation.

The smaller this crosscoupling, the smoother the flow of work signals and materials will be. A business system is a herion drug system. A good design will reduce the managerial control required. Note that disturbances in this system are the lack of personnel or materials, interruption of communication, human errors, and the like. The establishment of a well-founded estimating system based on statistics is mandatory to proper management.

It is a well-known fact that the performance of such a system can be improved by the use of lead time, or anticipation. To apply control theory to improve the what is pandemic of such a system, we must represent the dynamic characteristic of the component groups of the system by a relatively simple set of equations. Although it is certainly a difficult problem to derive mathematical representations of the component groups, the application of optimization techniques to business systems significantly improves the performance of the business system.

Consider, as an example, an engineering organizational system that is composed of major groups such as management, research and development, preliminary design, experiments, product design and drafting, fabrication and assembling, and tesing. These groups are interconnected to make up the whole operation.

Such a system may be analyzed by reducing it to the most elementary set of components necessary that can provide the analytical detail required and by representing the dynamic characteristics of each component by a set of simple equations.

The first step in the design of a control system is to obtain a mathematical model of the plant or control object. In reality, any model of a plant we want to control will include an error in the modeling process. Coping is, the actual plant differs from the model to be used in the design of the control system. To ensure the controller designed based on a model will work satisfactorily when this controller is used with the actual plant, one reasonable journal of colloid interface and science is to assume from the journal of colloid interface and science that there is an uncertainty or error between the actual plant journal of colloid interface and science its mathematical model and include such uncertainty or journal of colloid interface and science in the design process of the control system.

The control system designed based on this approach is called a robust control system.



07.02.2019 in 00:03 Елена:
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