Automatic Control Principle Research Articles

Growth of ferroelectric crystals from melt

Abstract This paper presents a review of the growth of ferroelectric crystals from the melt. The emphasis is placed on the physical principle of automatic diameter control and the response of the temperature fluctuation at the solid-melt interface to the crystal rotation and the growth of facets. Important phenomena commonly observed in as-grown crystals such as growth striations and domain structures are discussed. A one-to-one correspondence between the striations and the temperature fluctuations as well as between the ferroelectric domain structures and the striations is demonstrated. By using the growth striation as a time marker, the morphology of the solid-melt interface, including its evolution and stability, is studied.

Design of bipolar current source with amplitude up to 200 mA

One of the major requirements on the performance of a current source used for existing sensors is its amplitude stability. A method for designing a bipolar current source with amplitude up to 200 mA is developed. Its operating frequency is 10 kHz. The application of automatic control principles to the design of such a source makes the required amplitude stability possible. The circuit and its test data, including the maximum output amplitude, internal impedance, output regulation, and adjustment characteristic for an actual source, are given. This current source has successfully been used to excite the sensor of a continuous casting slag detector.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An introductory experiment in automatic process control using a microcomputer as controller

In this paper an experiment is described which illustrates automatic process control in a way suitable for introducing tertiary students to the principles of automatic control by negative feedback. The temperature of air in a simple air box is the variable controlled. The controller is an Apple II family microcomputer programmed for either on-off control, or for any of the usual combinations of proportional, integral and derivative action.

Automatic control of solar power stations

The principles of automatic control of the heliostat field of a solar power station are considered and specific peculiarities noted.

Principles of automatic control of sharp fractional distillation process

Principles of automatic control of sharp fractional distillation process

Book Review: Principles of Automatic Control

Book Review: Principles of Automatic Control

Principles of Automatic Control. 3rd edition. By MARTIN HEALEY. (English University Press Ltd, 1975.) [Pp. 352.] Price £2-95.

SUMMARY

Book Review: Principles of Automatic Control

Book Review: Principles of Automatic Control

A Laboratory Apparatus for Demonstrating Principles of Automatic Control

At leisurely speed the interrelated motions of mostly standard components in this versatile assembly furnish engrossing visual instruction on the role of feedback in a number of well known modes of automatic control. The controller-recorder furnishes a continuous graph of its action, which can be seen developing at all times. A few of of these modes and their graphs are shown.

Book Review: Principles of Automatic Control

Book Review: Principles of Automatic Control

Studies with an angiographic injector of automatic flow-rate control design.

With the growth of angiography as a branch of Radiology, several different types of pressure injectors have been developed to deliver contrast material rapidly into the vessels and the heart. Whether the injector is powered by an electric motor or by gas pressure, the operator can select the desired pressure to be delivered to the contrast medium in its syringe. The actual delivery rate of contrast media from the catheter into the vessel, then, is dependent on the internal bore and length of the catheter, on the viscosity of the contrast medium, and on the size of the connector or stopcock between the syringe and the catheter. Physical limitations of the system are imposed by the amount of pressure the injector can develop and by the strength of the catheter wall. The possibility of injuring tissue by the force of the jet or by the impaction of the tip and backlash movement of the catheter is the ultimate limitation of the injection procedure (4). To obtain the injection of a sufficient amount of opaque medium in a precise, short time-period one must know the capacity and characteristics of the injector, catheter and connections, and contrast medium. A previous study has shown that the best knowledge of flow-rate pressure relationships is obtained by pretesting the equipment in the laboratory under the same conditions as are to be used with the patient (3). It has been demonstrated that neither the Poiseuille formula for laminar flow or the Blasius formula for turbulent flow can be relied upon to predict rates of delivery of commonly used contrast media with a variety of catheters and injectors. The development of a new type of injector based on an automatic flow-rate control principle, has led to the expectation that a selected volume of one of several contrast media could assuredly be delivered through a variety of catheters. An evaluation was considered appropriate. Equipment and Methods A Viamonte-Hobbs injector, model 2000, was tested. The injector has two primary injection controls, one for the flow rate, with its scale graduated from 2.0 ml/sec. to 60 ml/sec.; and the other a timer, with its scale graduated from 0.2 second to 10 seconds. The two together determine the injection of a specific volume in a designated time. Additional features will not be considered here, but are well described elsewhere (6). The injector has a high-speed motor with a direct-coupled screw to drive the plunger into the barrel of the syringe. The syringe is of stainless steel and has a volume of 100 ml. The catheter was connected to the syringe with a Clay-Adams fitting. Injections were made through the catheter into a 100-ml graduated cylinder. An electric timer was used to verify the accuracy of the duration of the injection. Triplicate injections were made to check the reproducibility of performance.

Principle of mechanical automatic control of drilling parameters applied to machines for sinking boreholes

1. A double differential gear linked to the cutting head effects autocontrol of the drilling process in either rotary or rotary-percussive machines, and ensures withdrawal of the bit when jammed. 2. A machine with rotary action and autocontrol in terms of the drilling velocity, feed force, and torque on the bit, intended for drilling deep boreholes, can be constructed by using a mechanical differential gear connected to the cutting heads. 3. In rotary-percussive machines intended for drilling deep boreholes, the mechanical differential link between the machine and its striker unit must be replaced by a hydraulic or pneumatic force transmission, following the principles set out in the system of Fig. 1. When the operation of the striker unit is not controlled, the mechanism can conveniently be based on the first or second variant with an independently-operating pneumatic or hydraulic striker. In this case autocontrol will be of the drilling speed, feed thrust, and torque on the bit only. 4. The advantage of a differential gear connected to the cutting head of a drill is that it enables the motor to work at its rated power in all conditions, thus setting up favorable (uniform) conditions for the instrument's operation.

Automatic Control and Electronics

The past fifty years have seen the automatic control and electronic fields come close together and form an effective means for increasing man's productivity and his ability to control energy and materials. By extending automatic control concepts to new processes, by developing more flexible controls capable of changing their characteristics to optimize performance of the process being controlled, and by increasing the capability of the sensing means in difficult environments, man will be able to make even more effective his ability to control automatically in the years ahead. Electronics is increasingly able to provide physical means for providing the realization of automatic control principles and concepts. Increasing effort to achieve reliable electronic automatic control means must be continued in the years ahead to make possible the realization of the promised gains indicated by the automatic control theory. In addition, more use should be made of standardized design ranges of electrical and mechanical features so that all automatic control equipment can be made in less time and at a lower relative cost. The future appears bright for expanded use of automatic control and electronics as we look ahead for the next fifty years of the IRE.

Principles of automatic control

No disponible

Elements of position control

The paper offers a general descriptive survey of position control, including the characteristics of the usual input signal and load and their effects on performance. The basic principles of automatic control are applied to unmonitored and monitored position-control systems.Displacement-displacement servo systems are dealt with in some detail, the emphasis being on electric-non-thermionic amplifiers, and electric servo motors. The performance of these systems is discussed without any analysis, but the results of analysis are used for the recommended performance.