Vol 62 Iss. 1

Piezoelectric sensors of the volumetric type are widely used in the measurement of rapidly changing pressures. This is explained by their lack of inertia, the possibility of obtaining with their help quantitative and qualitative characteristics of the quantity being measured and linearity of the piezoelectric effect. ...

In the development of high-frequency continuous humidity control systems, the most labor-intensive part is developing efficient and operationally reliable sensors. Moisture sensors are usually in contact with bulk material or are in close proximity to it, being exposed to vibrations, temperature effects, abrasion, environmental influences (dampness, dustiness, chemical activity), i.e. interfering factors that distort the information.

Moisture content is one of the quality indicators of coal and its products. Measuring the moisture content of low-grade materials is a difficult problem and has not been finally solved.

Numerous methods of measuring the moisture content of solid, liquid and bulk materials are known: conductometric, based on the use of the relationship between moisture and the active resistance of the material; capacitive – between moisture and dielectric permittivity (more precisely – apparent capacitance); neutron; nuclear magnetic resonance – NMR, etc.

The process of drying phosphorite concentrate in a rotating drying drum (length 20 m, inner diameter 2.8 m) as an object of automatic control has been described in detail earlier.

One of the first stages in the synthesis of automatic control systems (ACS) is the preparation of the structural block diagram. Unlike the subsequent stages (mathematical synthesis of optimal dynamic characteristics, determination of dynamic characteristics of corrective devices, etc.), the method of synthesizing the structural block diagram is poorly developed. We are not aware of any engineering method for obtaining the structural block diagram of an ACS to be designed, even if it is an existing but not yet automated object.

To control inertial objects, two‑ and three‑position methods of control are widely used, but the quality of control in this case remains low.

Ensuring safety of movement of heavy duty open pit dump trucks in poor visibility conditions is a very urgent task, especially in the severe conditions of the Far North. Its solution will increase not only the accident free operation of dump trucks, but also their productivity. For example, at the open pit of the Central mine of the Apatit Combine, where BelAZ dump trucks are used, the number of days with fogs, snowfalls and blizzards reaches 300 per year. According to the current regulations, the movement of dump trucks is prohibited when visibility is less than 20 m. At visibility of 20 50 m, despite a sharp reduction in speed, the movement of dump trucks is not safe.

One of the first stages in the synthesis of automatic control systems (ACS) is the preparation of the structural block diagram. Unlike the subsequent stages (mathematical synthesis of optimal dynamic characteristics, determination of dynamic characteristics of corrective devices, etc.), the method of synthesizing the structural block diagram is poorly developed. We are not aware of any engineering method for obtaining the structural block diagram of an ACS to be designed, even if it is an existing but not yet automated object.

Let there be a non random signal (or a specific realisation of a random signal) y = y(t). Suppose this function is differentiable. …

The economic performance of the enterprise and a significant part of the current constraints, of course, are not absolute and depend on the tasks solved by the national economy as a whole. Their influence is manifested, first of all, through the pricing system, a given plan of conditions of financing, sales of products and material and technical supply. ...

The use of local systems of automatic control of the flotation process will be effective only with scientifically substantiated schemes and principles developed for a particular technological mode and equipment. In-depth study of the influence of various factors on the technological characteristics of the process is absolutely necessary. It is desirable to have a sufficient number of easily controllable factors that have a comprehensive impact on the technological performance of the process. Such factors include reagentconsumption rates, the amount of pulp entering the flotation, the level of pulp in the chambers of flotation machines, the pH of the pulp and its temperature.

In the high-frequency moisture-measuring system, developed at the Leningrad Mining Institute and designed for rapid determination of the moisture content of apatite concentrate, the output parameter is capacitance. …

The principle of autocompensation makes it possible to increase the accuracy of moisture control systems, which can be shown by an analysis of such systems from the position of information theory. The average value of negentropy – the amount of information required to obtain the limiting accuracy of the measured quantity q0, calculated from the sensor current, is about 7 decimal units. However, the sensor current contains not only useful information about the controlled moisture, but also interference (noise). ...

An AC induction machine in the general case can be represented as a dynamic system of moving and stationary circuits. ...

Of the many versions of ground-fault protection devices, the optimal one for distribution networks is the zero-sequence directional power relay with an electronic non-contact circuit.

The study of transients of a certain level or phase of voltage at moments of short-circuit at multiple repetition is complicated by a number of difficulties: 1) short-circuit must occur each time at a given phase of the voltage network; 2) the time of the closed state of the circuit (network) must exceed the duration of the transient with the subsequent automatic recovery of network parameters; observation or photographing the beginning of the leading edge of the transient process becomes impossible, since the entire process is conducted mainly with the help of cathode-ray oscilloscopes with triggered sweep.

Automation of mine hoisting installations with asynchronous drive is usually complicated during the deceleration and creep stage, when the hoisting conveyance must pass a strictly defined path, approach the dumping curves with a certain minimum speed and move at this speed until the completion of the hoisting cycle regardless of the magnitude and sign of the end-of-stroke load.

At mining enterprises of the Soviet Union, radio communication systems PAVS-2M, Nedra-II, Shakhter-II, and others were successfully used. Currently, attempts are being made to create equipment for measuring and transmitting information on the dynamics of production processes via radio communication channels. As is known, the transmission range and reliability of the communication channel under the conditions of mining enterprises are significantly enhanced when metal guides are present in the workings. ...

Automation of control at modern open pits makes increased requirements on information transmission systems, which due to the specifics of mining operations (mobility of controlled objects, their scattered location, etc.) as a physical communication channel use a radio channel. ...

Reference resonance circuits are promising for constructing energy-efficient electro-optical discrete light control systems. These systems can be used in annunciator panels at mining enterprises. The most interesting are circuits for programmed generation of bipolar pulses based on the principles of reference resonance. For research of control principles involved in generating such pulses, assessment of their complexity relative to switching circuits with resistive loads, and determination of the deviations of the generated pulses from a rectangular form, a breadboard using MP-42B transistors was developed. ...

One of the disadvantages of the existing practice of using computers for processing geological data is the lack of output devices for outputting information in graphical form. Two main functions of graphical output devices can be distinguished: 1) recording the final results of the calculations (documentation); 2) displaying information for the purpose of operational evaluation of the results of a previous iteration stage when solving problems by the fitting method. These functions determine the technical parameters of the device: in the first case, the decisive factor is the accuracy of the graphical plotting; in the second, it is the operating speed.

The study of conductivity and its temperature dependence is an effective method for studying the structure-sensitive characteristics of melts. However, there are few such publications, especially on sulfide melts of heavy nonferrous metals, which are of great importance in pyrometallurgical processes. Most researchers, when measuring the electrical conductivity of melts, use either the contact method or the non-contact method introduced into the practice of high-temperature measurements by A. R. Regel. In addition, the eddy current method can also be used for such measurements.

It is well known that there is no single measurement method for determining the modulus and phase of the complex transfer coefficient of two-port networks in the range of high and microwave frequencies. For definition of these quantities in the specified range of frequencies it is necessary to use a number of measuring devices working on different principles and providing far from equal accuracy of measurements. This diminishes the value of the measurement results and the possibility of their use, for example, for determining the dielectric constants of materials.

The behavior of an antenna in a well in terms of its input impedance is of interest in connection with the investigation of the possibility of enlarging wells in frozen rocks to large diameters by using microwave energy.

The electrode system and the heated frozen rock form a so-called operating capacitor, whose characteristics are capacitance and loss tangent. Knowing these characteristics, it is possible to determine all the elements of the high-frequency circuit that constitutes the power source of the technological process. ...