SU1275487A1 - Device for solving inverse problem of heat conduction - Google Patents

Abstract

The invention relates to analog computing. The purpose of the invention is to expand the functionality by: accounting for heat transfer coefficients. The device contains two integrated analog converters, three switches, two switches, an RC grid, a differential amplifier, a medium temperature setting unit, two comparators, a block of variables {Resistors, a block servo drive displacement transducer to N p, a dividing unit and a registration unit. 1 il.

Description

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This invention relates to analog computing.

The purpose of the invention is to expand the functionality by taking into account heat transfer coefficients.

The drawing shows the proposed device.

The device contains a digital-to-analog converter 1, a block of 2 variable resistors, a switch 3, an RC grid 4, a block 5 setting the medium temperature, a digital-analog converter 6, a differential amplifier 7, a switch 8, an inverter 9, an amplifier 10, a comparator 11, a switch 12, a switch 13 , a servo drive unit 14, a voltage-to-voltage converter 15, a switching unit 16, a dividing unit I7, a registration unit 18 and a comparator 19. The block 5 comprises a clock pulse generator 20, a counter 21 and a decoder 22.

The device works as follows.

The pulses of the generator 20 are recalculated by the counter 21. In accordance with the binary code of the state of the counter 21, at one or another output of the decoder 22, which are simultaneously the outputs of block 5, it appears

pulse duration i- where

f - frequency generator 20.

Output voltage Analogue of the temperature of the medium through the matching variable resistor 2 of the block and switch 3 is fed to the input of the RC grid 4. The inputs of the differential amplifier 7 receive the voltage of the internal nodal point of the RC grid 4 and the voltage from the output of the DAC 6, which is proportional to temperature in the inner nodal point of the body. If the current, analogous to the boundary heat flux, flows into the RC grid and the voltage at the DAC 6 output is greater than the voltage of the internal grid reference point, the error signal from the output of the differential amplifier 7 through the switch 8 is fed to the input of the amplifier 10. When The control inputs of the switches 3 and 13 pulses from block 5 close the corresponding keys. The signal from the output of the amplifier 10 hours. Through the key 12 and the Kth closed switch key 13 is fed to the control winding of the Kth servo drive of the unit 14, the rotor of which rotates.

changes the position of the K-th variable resistor of block 2, and, therefore, its resistance value, which leads to an increase in voltage

in the inner point of the RC grid. At the moment of time (K + 1) t, with the arrival of the next pulse from block 5, the next pair of keys in switches 3 and 13 is closed and the error signal controls the value (K + 1) of the variable resistor of block 2, and so on. Thus, each decision period is divided by pulses of block 5 into intervals (approximation areas). During each time interval, the resistance of one of the variable resistors of block 2 changes by an amount proportional to the error signal.

When changing the direction of current flow through the variable resistor of the block 2, the signal at the output of the comparator 19 changes its sign. As a result, the switch 8 is switched, and the error signal, coming from the output of the differential amplifier 7 through the switch 8 to the input of the inverter 9 and then through the amplifier 10, switch 12 and switch 13 to the control winding of the corresponding servo drive of the unit 14, increases the resistance of the variable resistor 2 and, therefore, an increase in the voltage in the internal IT of the RC grid, Thus,

the voltage at the internal point of the RC grid from the cycle to the cycle tends to coincide with the voltage at the output of the DAC 6. If, at the Kth step of the Nth cycle, the output voltage of the differential amplifier 7 becomes less than or equal to some predetermined small value determined by the voltage at the second input of the comparator 11 (Ug), then the output signal of the comparator becomes equal to zero, the key 12 opens and breaks the control circuit of the K-m variable resistor of block 2, the magnitude of which does not change in this cycle.

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Claims (1)

The solution is considered complete when the voltage at the output of the differential amplifier 7 (error signal) during the whole period of the solution is less than or equal to Ug, while the key 12 is open and the position of the variable motors of the resistors of the unit 2 does not change. 31 The registration unit 18 is intended to indicate the solution obtained. Switching unit 16 sequentially connects the outputs ;, of a multichannel displacement converter 15 to voltage to the first input of dividing unit 17, to the second input of which voltage U is applied, which simulates the proportionality coefficient between the value of the unsteady heat transfer coefficient and the value of the variable resistor of block 2 (voltage output at the output of the converter, the angle of rotation of the servo drive vada). The obtained values of the heat transfer coefficient are output to block 18. The invention, the Device, for solving the inverse problem of heat conduction, containing the first and second switches, the RC grid, the first and second digital-analog converters, the medium temperature setting unit, a group of discharge outputs inputs of the first and second digital-to-analog converters and with groups of control inputs of the first and second switches, the first and second comparators, amplifier, differential amplifier, unit ervoprivodov group of outputs of which is connected to a group of inputs specifying conduction block her variable resistors, the group output of which is connected with the group of information inputs of the first switch, the output of which is connected to the edge node RC-grid output of the first digital to analog converter connected to a group of input variables block re87. 4 sistors, the group of inputs of the servo unit is connected to the group of outputs of the second switchboard, which is based on the fact that, in order to expand the functionality by taking into account heat exchange coefficients, two keys, an inverter, a registration unit, a dividing unit, switching unit and motion to voltage converter, the output group of which is connected to the group of information inputs of the switching unit, the output of which is connected to the first input of the Split unit, the output of which is connected to the input of the registration unit, the target input and is the coefficient of heat exchange device is connected to the second input of the dividing block, a group of bit specifying unit outputs. the medium temperature is connected to a group of control inputs of the switching unit; the output of the first digital-to-analog converter is connected to the first input of the first comparator, the second input of which is connected to the boundary node of the RC grid whose central node is connected to the first inputs of the differential amplifier whose output is connected to the information input of the first key and the first input of the second comparator, the second input of which is connected to the input of the device reference voltage setting, the output of the second comparator is connected to the control it to the input of the second key, the information input of which is connected to the output of the amplifier, the input of which is connected to the output of the inverter and the first input of the first key, the second output of which is connected to the input of the inverter, the output of the second key is connected to the information input of the second switch.