A Comparative Analysis of Using the pH and Ammonia Calculation Algorithms in the Chemical Monitoring Systems at Thermal Power Plants

The reliability of thermal and mechanical equipment is largely associated with the introduction of cycle chemistry monitoring systems (CCMS). It is the operation of these systems that helps maintain the main parameters within the standardized ranges in a significantly more reliable manner and decrease the failure rate at power plants. Modern CCMSs use, as input information, the data of automatic chemical monitoring, laboratory chemical control, and thermal process parameters. Unfortunately, the large volume of chemical monitoring performed with the help of laboratory chemical control analyzers is a factor that causes less reliable operation of CCMS. The present study is intended for operating staff and employees of design organizations with the aim to decrease the volume of laboratory chemical control and reduce the sampling points load in terms of sampling flowrate. The possibility of applying indirect algorithms for calculating the most widely used indicators, such as pH and ammonia concentration, based on electrical conductivity measurements of direct and H-cationated samples in automatic chemical monitoring systems is considered. The results of calculation carried out using three algorithms for pH and ammonia concentration for laboratory and field conditions are given. A comparison of the results obtained from using three different methods for calculating the standardized indicators proceeding from experimental data is carried out.

Three-Phase and Five-Phase Motor Windings Common Point Potential Ripple with Respect to the Converter Zero Termina

The aim of the study is to determine the parameters characterizing the ripple of a motor's three- and five-phase windings common point potentials (for the star winding connection diagram) with respect to the converter zero point. One of the reserves for decreasing electromagnetically induced vibration of an electric motor with a rotating field is to increase the number of working winding phases. The study subject is a five-phase motor winding connected to a bridge converter, namely, its ability to reduce electromagnetically induced vibration in comparison with that in using a three-phase winding. The common point potential ripple parameters are studied, and an approach is proposed to estimating the amplitude modulation of the space-time voltage vector of three- and five-phase windings under the influence of the common point potential ripple with respect to the converter zero point. Theoretical studies were carried out using the Fourier series expansion method and vector analysis methods. To confirm the theoretical results, experimental studies of the prototypes of three-phase and five-phase synchronous motors with inductors made on the basis of permanent magnets were carried out. The main results have shown the following. With increasing the number of phases of the rotating field motor working winding connected to a bridge converter, the common point potential ripple amplitude with respect to the converter zero point decreases, and the ripple frequency increases. The product of ripple amplitude by frequency remains unchanged. It is assumed that the common point potential ripple of the motor multiphase winding with respect to the converter zero terminal results in the amplitude modulation of the space-time voltage vector. With increasing the number of winding phases, the modulation amplitude decreases, and the modulation frequency increases. A five-phase motor has a lower level of the working winding common point potential ripple with respect to the converter zero point in comparison with a three-phase motor. Thus, it can be assumed that there will be a lower level of electromagnetically induced vibration in using a simple converter operation algorithm. The obtained results can be used in designing electric traction systems with vector control on the basis of multiphase motors. With increasing the number of phases, the common point potential ripple amplitude in a multiphase winding with respect to the converter zero point decreases, and the ripple frequency increases. Thus, the common point potential ripple amplitude in a five-phase winding is 5/3 times less than that in a three-phase winding, and the ripple frequency increases by 5/3 times, respectively. With increasing the number of working winding phases, the amplitude modulation of the resulting space-time voltage vector decreases. This circumstance has a positive effect on decreasing the electromagnetically induced vibration.

Analysis of Foreign Experience in Using Flue Gas Purification Systems at Waste-to-Energy Plants

The existing method for selecting the structure of a power plant for thermally recycling municipal solid waste (MSW) in the Russian Federation does not address the matter of selecting all components of an energy complex operating on MSW, but places focus on determining the best accessible waste thermal neutralization technology. This generates the need to search for new methods and to select criteria of choosing the structure for each particular project. A comparative analysis of various structural schemes of waste-to-energy plants widely used outside of Russia will make it possible to reveal their main advantages and drawbacks, and to determine their application fields. The article describes the statistical indicators characterizing the operation of the flue gas purification system from acid gases, which can be applied in performing a feasibility study, intellectual property assessment, and in carrying out front-end engineering. For waste-to-energy plants constructed in an urban environment and aimed to operate with keeping to a minimum the gross emissions of acid gases into the atmospheric air, the use of a wet reactor system is recommended, which will ensure low emissions of HF, HCl, and SOx. The system with a wet reactor will make it possible to reduce gross emissions of harmful substances during the operation of large capacity waste-to-energy power plants and will be a justified choice in such case. In constructing medium capacity waste-to-energy plants (with a throughput of up to 350 000 t of MSW per annum), semi-dry and dry reactors can be used; for such plants, the technology involving the use of a semi-dry reactor is the most preferred one.

Arefyev Readings as a Means for Activating the Scientific Work of Technical University Students

The growing activity and interest of the students of technical universities in Moscow, Russia and abroad in participating in humanitarian conferences and the influence of these conferences on broadening the horizons, creative potential and general professional culture of engineers are demonstrated on the example of a multi-year cycle of humanitarian conferences held at a technical university.

A Model of Voltage Distribution and Change of Current in the Network Containing Unaccounted Electricity Consumption

The aim of the study is control of commercial losses in electrical grids, especially in low voltage grids, which is one of the priority lines of activities conducted by electric network companies. The complexity of solving this problem is stemming from the difficulty of exactly locating the commercial loss occurrence place under the conditions of extensively branched low and medium voltage electrical networks. Various methods are currently used to determine the commercial loss occurrence places. However, no effective methods have been created for determining the fact and place of unaccounted electricity consumption in networks under the conditions of performing remote analysis of networks based on the data from modern electricity meters used in the automated fiscal electricity metering system. These difficulties can be overcome by developing a model of voltage distribution and change of current in distribution networks of the 0.4--35 kV nominal voltage levels. A model of voltage distribution and changes of current for a network containing unaccounted electricity consumption is proposed. The effectiveness of using the proposed model has been theoretically substantiated; its applicability limits are defined, and the accuracy of the obtained results is estimated. Graphical representation of the proposed model, which is one of the electrical network digital imaging forms, can be used to analyze electrical networks for revealing if there is unaccounted electricity consumption in them. By using the proposed model of voltage distribution and change of current in the network, it is possible to represent the electrical network as a set of electrical parameters to analyze electrical networks for the presence of commercial losses.

Flux Leakage Reduction in Linear Vernier Generators Using High-Temperature Superconducting Elements

The article presents the results of studies aimed at improving the power performance indicators of linear electric generators for wave power plants by reducing the flux leakages using high-temperature superconducting (HTS) inserts placed in between the teeth. The generator design involving application of the Vernier principle for magnetic flux modulation with a translator in the form of a hollow cylinder is considered. Generators of this type are used in float wave power plants driven directly by a reciprocating float, which transmits large forces at a low motion speed. The calculations were carried out using the HTS properties modeling procedure based on representing the currents induced in a superconductor in the form of magnetic moments of these currents, which made it possible to simplify the analysis of the electromagnetic field in the generator without significant additional errors. As a result, the characteristics of the electromagnetic force longitudinal components and phase winding flux linkages versus the translator displacement have been obtained. The use of HTS inserts and a distributed winding in the stator made it possible to reduce the electromagnetic leakage losses and increase the interaction force between the stator and translator. However, since the additional outlays for the cooling system and thermal insulation of the HTS elements are commensurable with the generator cost, the obtained results on improving the power performance parameters do not allow an unambiguous statement to be made about the effectiveness of the considered technical solutions.

A Method for Calculating the Unsaturated Humid Air Flow Section Length in the Mechanical Draft Cooling Tower Sprinkler Channel

In the channels of mechanical-draft cooling tower sprinklers, a saturated air flow section may appear under certain initial conditions, the mass transfer intensity in which is limited by the steam content in the saturated air. For correctly calculating the heat and mass transfer processes in the cooling tower channel, it is necessary to have a method for determining the unsaturated air flow section length. Publications devoted to studying water cooling processes in the channels of mechanical-draft cooling tower sprinklers do not contain an assessment of the unsaturated air flow section length. A method for determining the unsaturated humid air flow section length in the mechanical-draft cooling tower sprinkler channels is proposed, which is based on the well-known criterion equations for calculating the heat transfer and mass transfer coefficients. The effect the initial air parameters have on the unsaturated air section length is studied, and graphic dependences of the unsaturated air section length are drawn up for each of the analyzed parameters. It is shown that the unsaturated humid air flow section length increases with increasing the initial air temperature. It is also found that the unsaturated air flow section length decreases with a growth in the relative air humidity. An increase in the air flow rate with a constant water flow rate leads to an increase in the unsaturated air flow section length. For the considered sprinkler channel, the saturated air region exists at an air temperature of 15°C and below, and for air temperatures above 25°C there is no saturated air flow section. It is shown that the conclusions drawn about the effect the initial air parameters have on the relative change in the unsaturated air flow section length are valid for channels of various shapes and geometric sizes. The proposed methodology and the results obtained can be used in designing mechanical-draft cooling towers and estimating their efficiency.

The Role of Vertically Integrated Structures in Industry Markets

The electric power industry is a basic sector of Russia's economy that creates necessary conditions for the activity of productive forces and life of the population. The results of electric power industry reorganization in our country are rather ambiguous. The structural changes were carried without taking the vertical integration principles in consideration, which had a significant impact on the pricing policy and investment programs. The results of studying the current state of the sector in the Russian Federation are presented, and recommendations on solving the existing problems based on the vertical integration principles are given. It is pointed out that vertically integrated companies that manage generation, distribution, transmission, and sales do not come in contradiction with the market conditions and, what is more, guarantee the power supply reliability. The relevance of this problem is stemming from the fact that the prices for electricity have a significant influence on the country economy as a whole. Under the currently existing conditions of the rapidly changing world policy, it is especially important to use vertical integration for gaining the maximum efficiency. Thus, these principles are the basis for creating an optimal market structure.

Setting up the Attribute Space of Periodic Time Dependencies for Dynamic Object Diagnostic Systems (Taking the Eye Retina as an Example)

The technology of testing dynamically and structurally similar aircraft models for flutter in subsonic wind tunnels using information and The article addresses techniques for setting up the attribute space of informative features of periodic signals recorded at the output of a dynamic object with an unknown structure in response to rectangular testing signals of different frequencies applied to the object input. The attribute space is used in developing expert systems for diagnosing the current state of an operating dynamic object. With a great variety of possible developing faults, the simplest practical techniques involving the use of characteristic points of change in the observed time dependencies yield a limited number of features with large mutual intersection domains. To expand the attribute space, it is proposed to use the expansion of input and output signals into a Fourier series for setting up a base of additional features. The proposed features characterize, depending on the testing conditions, the object’s transferring properties in the frequency domain from changes in its amplitude and phase characteristics. The test pulse frequency and duration serve as such conditions. For the convenience of comparing the object’s frequency responses variation pattern, two special procedures are used. The first procedure allows the observed time dependencies to be reduced to a single pseudo frequency of the test signals. The second procedure uses specially formed windows for subjecting individual fragments of the observed time dependencies to a spectral analysis. It is shown that, depending on the type of the frequency responses being analyzed, the techniques for their polynomial approximation, as well as integral estimates of frequency response individual domains can be useful. The polynomial approximation makes it possible to use the coefficients of the approximating polynomials as additional features, and the integration of individual characteristic domains of the frequency responses makes it possible to introduce dimensionless relative indicators that characterize the degree of change in the frequency responses depending on the experimental conditions. The considered techniques open the possibility to select additional features that can help distinguish both separate groups of faults and individual faults in operating objects. The study results are illustrated by the examples of analyzing the changes in electroretinograms that record changes in the eye retina biopotential in response to light flashes of different frequencies.

Information Literacy of a Foreign Language Teacher: An Analysis of Russian and European Professional Standards of Teachers

The introduction of information and communication technologies into the educational process began more than twenty years ago, along with the rapid spreading of computers around the world. However, not all educational institutions have supported the inclusion of information and communication technologies into the educational process for the above-mentioned quite a long period of time. Most likely, this was due to insufficient financial investments in modernization. In addition, insufficient attention was initially paid to training of teachers for working with digital technologies. At present, when information and communication competence has already been included into all international standards for teachers, it turned out that neither graduates from teacher training institutes nor teachers who have been working for already a long period of time have sufficient competencies for using digital technologies in practice. A comparative analysis of Russian and European professional standards for teachers is carried out, and the competencies they should possess are considered. Various versions of the information literacy definitions are given, which have undergone changes in the technological development process. Special attention is paid to the requirements for competencies of foreign language teachers in the field of digital technologies. The list of the currently available digital tools, including mobile devices, is discussed. The students actively use such technologies to learn languages, but to yield a really positive effect, digital tools should be integrated directly into the educational process in a professional manner. The experience of work with digital technologies gained by the teachers of the NRU MPEI Department of Foreign Languages is considered. A conclusion has been drawn, according to which a high level of information literacy enables teachers not only to change their own pedagogical methods, but also to open new horizons for their students, who, in turn, gain access to high quality education.