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 studied value and linearity of the piezoelectric effect...

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

Moisture content is one of the quality indicators of coal and coal products. Measurement of moisture content of materials of low goodness is a difficult task and not 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 constant (more precisely - apparent capacitance); neutron; nuclear magnetic resonance - yamr, etc.

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

One of the first stages in the synthesis of automatic control systems (ACS) is the preparation of the structural 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 scheme is poorly developed. We are not aware of any engineering method for obtaining the structural scheme of the structural scheme to be created by an automatic control system, even if it is an existing but not yet automated object.

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

Provision of safety of movement of heavy-duty dump trucks in poor visibility 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 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 meters. At visibility of 20-50 m, despite a sharp reduction in speed, the movement of dump trucks is not accident-free.

One of the main indicators that characterize the performance of dump trucks, is the weight of the transported rock mass. This indicator is also an important information factor of subsequent impact on the operational control and management of the production process of the mining enterprise. The weight of the transported rock mass is usually taken into account by calculating the number of trips of dump trucks, for which tentatively set the average capacity...

Let there is a non-random signal (or a specific realization 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 the cost of reagents, 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-metric system, developed at the Leningrad Mining Institute and designed for express determination of moisture content of apatite concentrate, the output parameter is the capacity...

The principle of autocompensation makes it possible to improve the accuracy of humidity control systems, which can be shown by analyzing such systems from the position of information theory. The average value of negentropy - the amount of information to obtain the ultimate accuracy of the measured quantity qo, calculated from the sensor current, is about 7 des. units. However, the sensor current contains not only useful information about the monitored humidity, but also interference (noise)...

An AC induction machine can generally be represented as a dynamic system of moving and fixed circuits...

Of the many variants of earth protection devices, the optimal one for distribution networks is the zero-sequence power direction relay with electronic contactless 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 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 oscilloscopes.

Automation of mine hoisting plants with asynchronous drive is usually complicated in the period of deceleration and pulling, when the hoisting vessel must pass a strictly defined path, approach the unloading 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 load.

At mining enterprises of the Soviet Union successfully used radio communication systems PAVS-2M, Nedra-ІІІ, Shahter-ІІІ and others. At present attempts are being made to create equipment for measuring and transmitting information on the dynamics of production processes using radio communication channels. As it is known, the transmission range and reliability of the communication channel in the conditions of mining enterprises are significantly increased in the presence of metal guides in mine workings...

Automation of management at modern quarries makes increased requirements to the systems of information transmission, which due to the peculiarities of mining production (mobility of control objects, their dispersion, etc.) as a physical communication channel use radio channel...

Reference resonance schemes are promising in the construction of energy-efficient electro-optical discrete light control systems. These systems can find application in light signaling boards at mining enterprises. The most interesting are the schemes of programmed formation of bipolar pulses on the principles of reference resonance. For research of control principles at formation of such pulses, estimation of complexity in relation to key circuits with active resistors, determination of deviations of formed pulses from rectangular form the layout on transistors MP-42B was developed...

One of the disadvantages of the existing practice of using computers for processing geological data is the lack of devices for outputting information in graphical form. Two main functions of graphic output devices can be distinguished: 1) fixing of final results of calculations (documentation); 2) display of information for the purpose of operative estimation of results of the previous stage of iteration when solving problems by the selection method. These functions determine the technical parameters of the device: in the first case the accuracy of graphical constructions is determinant, in the second case - the speed of.

The study of conductivity and its temperature dependence is an effective method of studying the structure-sensitive characteristics of melts. However, there are few publications of this kind, especially on sulfide melts of heavy non-ferrous metals, which are important in nitro-metallurgical processes. Most researchers in 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. At the same time, 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 transmission coefficient of quadrupoles in the range of high and ultrahigh 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 not equal accuracy of measurements. This reduces the value of measurement results and the possibility of their use, for example, to determine the dielectric constants of materials.

The behavior of an antenna in a borehole in terms of its input impedance is of interest in connection with the investigation of the possibility of extending boreholes in frozen rocks to large diameters using microwave energy.

The electrode system and the heated frozen rock form a so-called working capacitor, whose characteristics are electrical capacitance and tgδ (loss angle). Knowing these characteristics, it is possible to determine all elements of the high-frequency circuit that forms the energy source of the technological process...