Статті в журналах: "Integral losses"

1

Mavrin, A. A., A. V. Demura, D. S. Leont'ev, and V. S. Lisitsa. "Radiatsionnye poteri deytronov, tritonov i al'fa-chastits na ionakh vol'frama v plazme tokamakov-reaktorov ITER i EU–DEMO." Письма в Журнал экспериментальной и теоретической физики 118, no. 11-12 (12) (December 15, 2023): 816–25. http://dx.doi.org/10.31857/s1234567823230052.

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Integral radiative losses of deuterons, tritons, and alpha particles on impurity tungsten ions have been calculated for the first time within the statistical theory of the atom for the designed operational regimes of the ITER and EU-DEMO tokamak reactors. It was previously shown within the statistical theory of the atom that specific radiative losses of this new ion channel are comparable with specific electron radiative losses, which also include losses due to bremsstrahlung, radiative and dielectron recombination. Integral radiative losses have been calculated within the numerical model of fusion power isolines, which was previously proposed to study the operational space and design regimes of tokamak reactors. Spatial distributions of the tungsten density with various degrees of peaking in the center of a plasma column have been considered to study the influence of the accumulation of the impurity on integral radiative losses. It has been found that the studied new channel adds about 20 and 30% to the total integral radiative losses on tungsten in the ITER and E-U‑DEMO tokamak reactors, respectively. Consequently, this channel of radiative losses should be taken into account to examine in more detail the working scenarios of these devices.

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2

Zajtsev, F. S., A. P. Smirnov, and P. N. Yushmanov. "Integral stochastic alpha particle losses in a tokamak reactor." Nuclear Fusion 26, no. 10 (October 1, 1986): 1311–17. http://dx.doi.org/10.1088/0029-5515/26/10/004.

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3

Statra, Yazid, Hocine Menana, and Bruno Douine. "Integral Modeling of AC Losses in HTS Tapes With Magnetic Substrates." IEEE Transactions on Applied Superconductivity 32, no. 2 (March 2022): 1–7. http://dx.doi.org/10.1109/tasc.2021.3139383.

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4

Blakyta, Ganna, Olena Matusova, Halyna Lanovska, and Victor Adamenko. "Integral assessment of business environment security." Problems and Perspectives in Management 15, no. 4 (December 25, 2017): 280–92. http://dx.doi.org/10.21511/ppm.15(4-1).2017.12.

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The methodological approach to the integral assessment of business environment security is developed in the article; the blocks of factors of business environment security are identified and the indices which affect the formation of economic security of entrepreneurship are analyzed. The integral indicator for assessing business environment security is based on 6 indicators, which are the most significant elements of the business environment formation: the availability of basic economic freedoms, the favorable organizational conditions for doing business, the state of political and legal system, the level (quality) of life, resource provision and infrastructure development, innovation development. A comparative analysis of the integral indicator of business environment security of Ukraine with the Baltic countries, Black Sea region countries and the Visegrad Group countries is carried out. The article identifies interdependence between the business environment security and the share of unprofitable enterprises. The functional relationship of the business environment security with the number of bankrupt enterprises and the level of enterprises losses is substantiated as well. The model shows that the increase of environmental security leads to the decrease of a number of bankruptcies exponentially. The negative and positive factors which influence the formation of economic security of entrepreneurship are revealed.

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5

Ratcliffe, Matthew, and Louise Richardson. "Grief over Non-Death Losses." Passion: Journal of the European Philosophical Society for the Study of Emotions 1, no. 1 (June 9, 2023): 50–67. http://dx.doi.org/10.59123/passion.v1i1.12287.

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Grief is often thought of as an emotional response to the death of someone we love. However, the term “grief” is also used when referring to losses of various other kinds, as with grief over illness, injury, unemployment, diminished abilities, relationship breakups, or loss of significant personal possessions. Complementing such uses, we propose that grief over a bereavement and other experiences of loss share a common phenomenological structure: one experiences the loss of certain possibilities that were integral to—and perhaps central to—the unfolding structure of one’s life. Grief can thus be conceived of in a broad but still univocal way. To develop this position, we focus on the example of grief over involuntary childlessness, where lack of a concrete, historical object of emotion serves to make explicit the way in which grief concerns future possibilities. We go on to suggest that the phenomenological complexity, diversity, and prevalence of grief are obscured when approached via an abstract, simplified conception of bereavement.

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6

Mimic, Dajan, Christoph Jätz, and Florian Herbst. "Correlation between total pressure losses of highly loaded annular diffusers and integral stage design parameters." Journal of the Global Power and Propulsion Society 2 (August 27, 2018): I9AB30. http://dx.doi.org/10.22261/jgpps.i9ab30.

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Diffusers convert kinetic flow energy into a rise in static pressure. This pressure recovery is the primary aerodynamic design objective for exhaust gas diffusers in power-generating steam and gas turbines. The total pressure loss is an equally important diffuser design parameter. It is strongly linked to the pressure recovery and the residual kinetic energy of the diffuser outlet flow. A reduction benefits the overall thermodynamic cycle, which requires the adjacent components of a diffuser to be included in the design process. This paper focuses on the total pressure losses in the boundary layer of a highly loaded annular diffuser. Due to its large opening angle the diffuser is susceptible to flow separation under uniform inlet conditions, which is a major source for total pressure losses. However, the unsteady tip leakage vortices of the upstream rotor, which are a source of losses, stabilise the boundary layer and prevent separation. Experiments and unsteady numerical simulation conducted show that the total pressure loss reduction caused by the delayed boundary layer separation exceed the vortex-induced losses by far. This flow interaction between the rotor and diffuser consequently decreases the overall total pressure losses. The intensity of the tip leakage vortex is linked to three rotor design parameters, namely work coefficient, flow coefficient and reduced blade-passing frequency. Based on these parameters, we propose a semi-empiric correlation to predict and evaluate the change in total pressure losses with regards to design operating conditions.

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7

Suartika, I. Made, Rukmi Sari Hartati, and I. B. G. Manuaba. "Damping Harmonic Distortion Using Active Filter with PID Control at Udayana University Faculty of Engineering Bukit Jimbaran." Journal of Electrical, Electronics and Informatics 2, no. 2 (December 18, 2018): 29. http://dx.doi.org/10.24843/jeei.2018.v02.i02.p02.

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Increased THD (Total Harmonics Distortion) in the utility, caused by the increasing operation of non-linear loads. High THD current (THDi) will affect the increase of power losses in the power system. In this study, THD analysis of the simulation results was performed according to IEEE 519-2014 standard on existing condition, shunt active filter operating condition and shunt active filter operating conditions with PID (proportional integral derivative) control, also analyzed losses before and after harmonic impact. The result of losses analysis on existing condition: losses phases R 3.38%, phase S 2.29%, phase T 3.33%. Total losses on existing condition 9.01%. Operation with active shunt filter is obtained losses for phase R 1.60%, phase S 2.46%, phase T 1.67%, so the total losses become 5.73%. While using the active filter with PID control for losses phase R 1.02%, phases S 0.89%, phases T 0.99%, so the total losses fell to 2.18%

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8

Artemenko, М. Yu, V. М. Mykhalskyi, and І. А. Shapoval. "Active filtration theory of multiphase power supply sys tems aimed at minimizing the power loss in the transmission line." Reports of the National Academy of Sciences of Ukraine, no. 11 (2020): 39–50. http://dx.doi.org/10.15407/dopovidi2020.11.039.

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The active filtration theory of multiphase power supply systems aimed at minimizing the power losses in the transmission line has been further developed. New relations are substantiated, and a new physical content is given for the instantaneous active current and the instantaneous apparent power, which take into account the dependence of the transmission line resistance ratio and correspond to similar integrated values of the periodic mode of a multiphase power supply system. It is shown that the instantaneous and integral values of the minimum possible losses are proportional to the square of the load power and inversely proportional to the short-circuit power. These values can be used to determine the power factors of a given load and gain coefficients for power losses. The calculated ratios for the gain coefficients for the instantaneous and integral power losses when using a shunt active filter with control strategies that form in the transmission line vectors of the active current according to the proposed formulas were obtained. The results of computer simulation confirmed the adequacy of all modified relations for the basic concepts of the active filtration theory of multiphase power supply systems and the advantages of the proposed active filtration strategies.

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9

Goryslavets, Yu M., O. I. Gluhenky, and V. I. Zalozny. "MODELING OF ELECTROMAGNETIC PROCESSES IN INDUCTION CHANNEL FURNACES TAKING INTO ACCOUNT METAL FRAMES." Praci Institutu elektrodinamiki Nacionalanoi akademii nauk Ukraini 2023, no. 64 (May 8, 2022): 64–69. http://dx.doi.org/10.15407/publishing2023.64.064.

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On the basis of the formulated mathematical model for the study of electromagnetic processes in a two-phase (two-inductor) induction channel furnace, electrical losses in the metal frameworks of the furnace were calculated for vari-ous options for their sectioning. The influence of the phase angle between the voltages feeding the inductors of the fur-nace on the distribution of specific and integral losses in the frames is determined. Practical recommendations for re-ducing these losses in order to increase the efficiency of melting furnaces are presented. Ref. 5, fig. 5.

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10

Giussani, Luca, Luca Di Rienzo, Massimo Bechis, and Carlo de Falco. "Losses Computation in Thin Conductive Sheaths of Power Cables via an Integral Approach." IEEE Transactions on Magnetics 57, no. 6 (June 2021): 1–4. http://dx.doi.org/10.1109/tmag.2021.3065673.

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11

Roy, T., T. K. Sarkar, and M. Swaminathan. "Surface integral formulation for calculating conductor and dielectric losses of various transmission structures." IEEE Transactions on Microwave Theory and Techniques 43, no. 1 (January 1995): 176–85. http://dx.doi.org/10.1109/22.362993.

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12

Lapuzin, Alexander, Valery Subotovich, Yuriy Yudin, Svetlana Naumenko, and Ivan Malymon. "Studying the Effect of the Tangential Nonuniformity of Flow Parameters on Gas Dynamic Performances of the Nozzle Cascades of Turbine Machines." NTU "KhPI" Bulletin: Power and heat engineering processes and equipment, no. 1-2 (December 28, 2022): 23–31. http://dx.doi.org/10.20998/2078-774x.2022.01.03.

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Aerodynamic efficiency of the nozzle cascades of steam and gas turbines is defined by many factors and one of them is the tangential and radial nonuniformity degree of the parameters of a spatial flow behind the cascades. The averaging of these parameters enables the determination of the integral parameters of the cascades, in particular two flow angles and the velocity angle or the kinetic energy loss coefficient. The angle that takes into account the level of the averaged radial component of the velocity defines the level of kinematic losses in the cascade. Even in the case of the cylindric boundaries of the cascade this angle differs from zero and kinematic losses decrease the cascade efficiency by 30 to 50 percent. This scientific paper gives the results of experimental investigations of the effect of the circumferential nonuniformity of the velocity and the angles of the spatial flow on kinematic losses at different radii of the nozzle cascade of the last stage of the steam turbine and the nozzle cascade of the first stage of the gas turbine. The kinetic energy loss coefficient and the coefficient of total losses were suggested as the integral characteristics of the cascades. In the case of cylindric boundaries of the stage the total loss-to-kinetic energy loss ratio is noticeably decreased during the transition from the average zone to the zone of end losses. However, in the peripheral zone of the nozzle cascade of the last stage of steam turbine total losses are three times higher than kinetic energy losses due to the fact that the radial component of the velocity behind the cascade is much higher than the flow rate component and the level of the losses of kinetic energy is not high.

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13

Chubaievskyi, V., H. Blakyta, O. Bogma, I. Shtuler, and T. Batrakova. "Protection of information resources as an integral part of economic security of the enterprise." Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, no. 4 (August 30, 2022): 117–22. http://dx.doi.org/10.33271/nvngu/2022-4/117.

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Purpose. To build a mathematical model and algorithms for optimizing the losses that the company may suffer from information threats and the costs necessary to prevent these losses. Methodology. General and special methods of cognition were used to perform scientific research: comparative analysis, logical generalization and systematization, mathematical abstraction, system-oriented analysis. Findings. A mathematical model and optimization algorithms are proposed for using an improved methodological approach to the formation of information security of the enterprise in terms of minimizing costs and losses. This allows one not only to analyze threats and determine the weight of factors influence but also to determine effective tactics and strategies to minimize their consequences. Originality. During the research, a mathematical model and algorithms of optimization of losses from information threats and expenses of the enterprise for their neutralization are created. It also allows us to predict the likely consequences of probable threats. Methodological approaches to the formation of the optimal level of costs to maintain the appropriate level of security have been improved. It is shown that the analysis of information risks and threats of assessment of financial and economic stability of the enterprise to information danger should be accompanied by comparison in a dynamic mode of the corresponding economic indicators. The introduction of a methodological approach to comparing the real and optimal values of the integrated indicator of resilience allows managers to assess trends and directions of projected information threats and the need to allocate sufficient resources for protection. Practical value. The results of the study can be used by practitioners to implement effective management of information risks and neutralize their impact on economic indicators of the enterprise and by scientists to develop strategies and methods to neutralize information threats to financial and economic stability, production and economic stability and organizational and economic stability, the latest methods of enterprise risk management.

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14

Brekotkina, A. D., E. Yu Semakina, P. N. Brodnev, and V. A. Chernikov. "Justification of nonstandard geometry of exhaust duct of steam turbine low pressure cylinder: case study of K-300-240-2 LMZ." Vestnik IGEU, no. 5 (December 30, 2020): 5–13. http://dx.doi.org/10.17588/2072-2672.2020.5.005-013.

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Presently the losses of kinetic energy in the exhaust duct of low-pressure cylinder are considerable, since numerous spacer bars and directing plates are located inside. A fundamentally new approach is required to design the exhaust duct of LPC without internal elements in water passage and providing the decline of losses due to improvement of the diffuser form and collapsible chamber. The flow modeling in the considered exhaust duct design was carried out by the numerical RANS method with the SST turbulence model. To validate the CFD model, the results of the previous experimental studies of the basic design model were used. The comparison of the integral aerodynamic characteristics of the exhaust duct was carried out. For the basic variant of the exhaust duct, the variant without internal elements, and also for the variant without internal elements and with new geometry of the collapsible chamber, according to the results of the numeral experiment, distribution of pressure and vector fields of speeds in the exhaust nozzle are received and the integral parameters of the exhaust duct are defined. Advantage of the integral descriptions of the exhaust duct without internal elements and with a new form of collapsible chamber is proven. They are the coefficient of internal losses of the exhaust duct, the coefficient of kinematics unevenness of the stream, and the coefficient of repressuring in an axial-radial diffuser. It has been established that a new approach of geometry of the exhaust duct of LPC provides the improvement of their aerodynamic qualities when designing new high-powered steam-turbines to operate in TPP and NPP. The advantage of losses decline of energy in the exhaust duct is multiple, because the number of LPC streams in modern seam-turbines can amount up to eight.

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15

Devineni, Gireesh Kumar, Aman Ganesh, and Neerudi Bhoopal. "Power Loss Analysis in 15 Level Asymmetric Reduced Switch Inverter Using PLECS Thermal Model & SIMULINK Precise Models." Journal Européen des Systèmes Automatisés 54, no. 1 (February 28, 2021): 73–84. http://dx.doi.org/10.18280/jesa.540109.

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Power losses are the most critical metrics in power converters analysis and has a significant impact on economic and technological assessments due to its sufficient approximation. This article aims to prove that the power losses (Switching & Conduction losses) are very low in low frequency switching modulation in contrast with high switching frequency modulation. Two switching modulation techniques Phase Disposition (PD-multi carrier-based pulse width modulation at high switching frequency) and Selective Harmonic Elimination Pulse Width Modulation (SHEPWM-fundamental switching frequency) are considered for the power loss assessment in 15-level reduced switch asymmetric multi-level inverter. This work proposed a simplified model for calculation of switching losses in multilevel inverters using MATAB SIMULINK. Further, the thermal model of the proposed inverter is implemented on PLECS for analyzing the power losses. The comparative analysis of switching and conduction losses of the proposed inverter with the PLECS thermal model and MATLAB precise models are integral part of this research.

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16

Tsukerman, Igor. "Computational Electromagnetics: A Miscellany." J 4, no. 4 (December 15, 2021): 881–96. http://dx.doi.org/10.3390/j4040060.

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The paper presents a miscellany of unorthodox and, in some cases, paradoxical or controversial items related to computational and applied electromagnetics. The topics include a definition of the magnetic source field via a line integral, losses in electric power transmission vs. losses in photonics, homogenization of periodic electromagnetic structures, spurious modes, models of plasmonic media, and more. It is hoped that this assortment of subjects will be of interest to a broad audience of scientists and engineers.

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17

Naumov, Valeriy, and Konstantin Samouylov. "Resource System with Losses in a Random Environment." Mathematics 9, no. 21 (October 22, 2021): 2685. http://dx.doi.org/10.3390/math9212685.

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The article deals with queueing systems with random resource requirements modeled as bivariate Markov jump processes. One of the process components describes the service system with limited resources. Another component represents a random environment that submits multi-class requests for resources to the service system. If the resource request is lost, then the state of the service system does not change. The change in the state of the environment interacting with the service system depends on whether the resource request has been lost. Thus, unlike in known models, the service system provides feedback to the environment in response to resource requests. By analyzing the properties of the system of integral equations for the stationary distribution of the corresponding random process, we obtain the conditions for the stationary distribution to have a product form. These conditions are expressed in the form of three systems of nonlinear equations. Several special cases are explained in detail.

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18

Brambilla, R., F. Grilli, and L. Martini. "Integral Equations for Computing AC Losses of Radially and Polygonally Arranged HTS Thin Tapes." IEEE Transactions on Applied Superconductivity 22, no. 4 (August 2012): 8401006. http://dx.doi.org/10.1109/tasc.2012.2191405.

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19

Brambilla, Roberto, Francesco Grilli, Doan N. Nguyen, Luciano Martini, and Frédéric Sirois. "AC losses in thin superconductors: the integral equation method applied to stacks and windings." Superconductor Science and Technology 22, no. 7 (June 10, 2009): 075018. http://dx.doi.org/10.1088/0953-2048/22/7/075018.

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20

PEPLOW, ANDREW T. "NUMERICAL PREDICTIONS OF SOUND PROPAGATION FROM A CUTTING OVER A ROAD-SIDE NOISE BARRIER." Journal of Computational Acoustics 13, no. 01 (March 2005): 145–62. http://dx.doi.org/10.1142/s0218396x05002517.

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A boundary integral equation is described for the prediction of acoustic propagation from a monofrequency coherent line source in a cutting with impedance boundary conditions onto surrounding flat impedance ground. The problem is stated as a boundary value problem for the Helmholtz equation and is subsequently reformulated as a system of boundary integral equations via Green's theorem. The numerical solution of the coupled boundary integral equations by a simple boundary element method is then described. Predictions of A-weighted insertion losses for a traffic noise spectrum are made illustrating the effects of depth of the cutting and the profile of the associated noise barrier.

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21

Bobiy, B. V. "Towards an Assessment of the Severity of Human Casualties in Terrorist Acts Committed by Conventional Means of Destruction." Disaster Medicine, no. 4 (December 2023): 5–10. http://dx.doi.org/10.33266/2070-1004-2023-4-5-10.

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Summary. Objectives of the study are as follows: on the basis of studying and analyzing methodological approaches to assessing the severity of human losses in terrorist acts committed with the use of conventional means of destruction to develop proposals for further improvement of these methodological approaches; to assess the severity of human losses being the result of terrorist attacks committed on the territory of Russia in 1999-2005. Materials and research methods. The materials of the research are normative and methodical documents regulating the procedure of assessment of human losses in emergency situations, including terrorist acts; reports of territorial centers for disaster medicine about terrorist acts committed on the territory of Russia in 1999-2005; data of survey maps and expert evaluation of the subject of the research; scientific works and publications devoted to methods of assessment of severity of consequences of emergency situations and terrorist acts. The following scientific methods were used in the study: content analysis method, method of expert evaluation, statistical and analytical methods. Results of the study and their analysis. The results of the study of methodological approaches to assessing the severity of human losses in terrorist attacks and other emergencies are presented. Reasoned proposals are made to improve the methodological approaches to assessing the severity of human losses in terrorist acts and to use a comprehensive integral methodological approach for this purpose. The results of the research have shown that the existing technologies of determining the severity of human losses in terrorist attacks do not allow to have objective and complete reliable data on the injured, on the volume and specificity of work performed by medical workers in providing medical care and medical evacuation in the course of saving lives and preserving health of the injured in terrorist attacks. Using the proposed complex integral methodological approach, an assessment of the severity of human losses in terrorist acts committed on the territory of Russia in 1999-2005 is given.

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22

Slama, Vaclav, David Simurda, Ladislav Tajc, Bartolomej Rudas, Jindrich Hala, Martin Luxa, and Tomas Radnic. "Pressure losses reduction in a steam turbine compact valve." EPJ Web of Conferences 264 (2022): 01042. http://dx.doi.org/10.1051/epjconf/202226401042.

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Valves are integral parts of modern steam turbines. They provide flexible operations and fast load changes which have become more often due to the increasing share of renewable energy. Along with this, the low pressure loss is required for guaranteed operation conditions. This paper is concerned with investigation of pressure losses in the compact valve, which is used as a valve for the intermediate-pressure turbine part, and its geometry modification to lower overall pressure losses. The investigation is based on results of numerical simulations which were carried out in the Doosan Skoda Power Company using a package of ANSYS software tools. Source of increased pressure losses in the compact valve is identified and a way of its reduction is proposed based on the comparison of the current results with data from a typical control valve model. Data analysis is provided in the paper.

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23

Shishkin, S. F., A. S. Shishkin, and V. B. Ponomarev. "Calculation of pressure losses during pneumatic transport." NOVYE OGNEUPORY (NEW REFRACTORIES), no. 12 (January 23, 2020): 51–55. http://dx.doi.org/10.17073/1683-4518-2019-12-51-55.

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A method for calculating pressure losses during pneumatic transport is considered with the aim of choosing the most favorable operating mode, which allows to reduce the consumption of compressed air. It has been established that the generally accepted formulas for calculating pressure losses along the path, calculated as the sum of the pressure losses for pure gas and material, do not explain the fact of the initial decrease in pressure losses with increasing air flow rate, and then their growth. The importance of accounting for changes in air density and air flow velocity along the length of the pipe, as well as the need to take into account the overlap of part of the pipeline section with material in the case of high concentrations, is shown. It is proposed to determine the pressure loss using the Bernoulli equation in integral form, for example, the Gauss method using eight nodes. The applicability of the method for calculating both straight and inclined sections of pipelines is established. The experimental results of studying and analyzing the proposed isothermal model in a vacuum pneumatic transport laboratory installation are presented. An example of calculating the pressure loss for an industrial pneumatic conveying system with a pipe length of 450 m and an inner diameter of 147 mm at various flow rates of the material is shown. Ill. 4. Ref. 21. Tab. 1.

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24

Maheeth, P. V. S., P. Srividya Devi, and P. Sirisha. "Artificial Intelligent Technique based Double-Frequency Analysis on a Single-Phase Grid-connected Inverter." E3S Web of Conferences 309 (2021): 01144. http://dx.doi.org/10.1051/e3sconf/202130901144.

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Now a days more power losses can be seen in grid connected inverter. In order to reduce that double frequency in single phase grid inverter with Artificial Intelligent based fuzzy control is implemented. The inverter has two operating units High Frequency Unit (HFU) and Low Frequency Unit (LFU), low frequency reduce switching losses and high frequency suppress the symphonious currents. The fuzzy logic method expected towards deliver high yield, low total symphonious distortion, rapid response. Finally Total Symphonious Distortion (THD) contrasted among fuzzy including Integral controls (PI). The results are validated by using MATLAB/Simulink.

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25

Modest, M. F., and H. Abakians. "Evaporative Cutting of a Semi-infinite Body With a Moving CW Laser." Journal of Heat Transfer 108, no. 3 (August 1, 1986): 602–7. http://dx.doi.org/10.1115/1.3246978.

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The formation of a deep groove by evaporation on a moving semi-infinite solid is considered. Evaporative removal of material is achieved by focusing a high-power, highly concentrated Gaussian laser beam of constant wattage (CW laser) onto the surface of the solid. Assuming thermal losses due to conduction and convection to be relatively minor, these losses are treated in an approximate fashion using a simple integral method. The relevant nonlinear partial differential equations are solved numerically, and results for groove depth and shape are presented for a variety of laser and solid parameters.

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26

Attou, A., and L. Bolle. "Integral formulation of balance equations for two-phase flow through a sudden enlargement Part 1: Basic approach." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 211, no. 5 (May 1, 1997): 387–97. http://dx.doi.org/10.1243/0954406971522132.

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A general expression of irreversible losses related to two-phase flows through a sudden enlargement is derived from basic balance equations (mass, momentum and energy). The need to take into account void fraction and quality changes is emphasized for some one-fluid flows. From a comparison with several experimental results, it is concluded that a void fraction decrease downstream of the enlargement must be considered in order to predict satisfactorily pressure variations on the basis of the momentum balance procedure. When expressed in the form of a fraction of reversible pressure recovery, dissipation losses appear to depend strongly on the quality. Their minimum value is observed for a larger quality value when the pressure of the system is increased.

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27

Korotin, Alexander, Vladimir V’yugin, and Evgeny Burnaev. "Mixability of integral losses: A key to efficient online aggregation of functional and probabilistic forecasts." Pattern Recognition 120 (December 2021): 108175. http://dx.doi.org/10.1016/j.patcog.2021.108175.

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28

Taroncher, M., J. Hueso, S. Cogollos, B. Gimeno, V. E. Boria, A. Vidal, H. Esteban, and M. Guglielmi. "Accurate consideration of metal losses at waveguide junctions using admittance and impedance integral equation formulations." Radio Science 40, no. 6 (December 2005): n/a. http://dx.doi.org/10.1029/2004rs003225.

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29

Mnasri, Chaouki, Dhouha Chorfi, and Moncef Gasmi. "Robust Integral Sliding Mode Control of Uncertain Networked Control Systems with Multiple Data Packet Losses." International Journal of Control, Automation and Systems 16, no. 5 (July 25, 2018): 2093–102. http://dx.doi.org/10.1007/s12555-017-0636-7.

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30

Naprienko, Anastasiia S., and Dmitry А. Shtein. "Optimization of switching losses of the Weinberg converter." International Journal of Power Electronics and Drive Systems (IJPEDS) 14, no. 3 (September 1, 2023): 1544. http://dx.doi.org/10.11591/ijpeds.v14.i3.pp1544-1552.

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Анотація:

DC-DC converters are widely used in hybrid power supply systems. A buffer source of electrical energy (most often a battery bank) and its charging and discharging devices are integral parts of such systems. In systems where the battery bank voltage is less than the DC-bus voltage and galvanic isolation is not required, the Weinberg converter is widely used as a discharge device, for example, in spacecraft power supply systems. The current trend in the development of hybrid power supply systems is to increase the power density of the system. Increasing the operating frequency is the simplest and most effective way to increase the power density of converter. A differential characteristic of this converter is the zero-current switching (ZCS) of transistors, which occurs due to the influence of the leakage inductance of coupled-inductors and the leakage inductance of the transformer. The paper presents an analysis of the influence of leakage inductances on the operation of the converter and a method of determining a level of turn on switching losses of transistors, which allows to ensure the necessary level of efficiency of the converter. The results of simulation modeling of the converter confirm the effectiveness of this method.

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31

Abakians, H., and M. F. Modest. "Evaporative Cutting of a Semitransparent Body With a Moving CW Laser." Journal of Heat Transfer 110, no. 4a (November 1, 1988): 924–30. http://dx.doi.org/10.1115/1.3250594.

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The formation of a groove by partial evaporation of a moving semi-infinite and semitransparent solid is considered. Evaporative removal of material is achieved by focusing a high-power, highly concentrated Gaussian laser beam of continuous wave (CW) onto the surface of the solid. Surface heat losses due to radiation and convection are assumed to be negligible, and conductive losses are treated in an approximate fashion using a simple integral method. The relevant nonlinear partial differential equations are solved numerically, and results for groove depth and shape are presented for a variety of laser and solid parameters.

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32

Shkolnyk, Inna, Tomasz Pisula, Liliia Loboda, and Natalia Nebaba. "Financial crisis of real sector enterprises: an integral assessment." Investment Management and Financial Innovations 16, no. 4 (December 26, 2019): 366–81. http://dx.doi.org/10.21511/imfi.16(4).2019.31.

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Successful crisis resolution of the enterprise depends heavily on its timely detection, which is facilitated by the use of forecasting models. This allows understanding the scale of the problems in a timely manner and developing the appropriate measures, applying various financial mechanisms to prevent it, and in case of occurrence, reducing the amount of losses. In this context, it is important to choose the most optimal informational model that would provide the most objective forecasts, considering the financial activity peculiarities of the analyzed enterprise. Given a wide list of models that predict the financial crisis, there is a need to analyze and select the most accurate model for enterprises in the real economy. Ten Ukrainian machine builders are used to assess the bankruptcy probability using the most popular models; a taxonomic analysis was carried out, which allows systematizing a large amount of data and analyzing their impact on enterprise development. An integral index was determined, which allowed predicting the financial performance dynamics. For each enterprise, ten indicators were used characterizing their financial state for the period 2014–2018. It is substantiated that the selected models differ from each other by the set of initial data and the number of coefficients from four to seven. It is also determined that the efficient use of studied models is quite different; so when choosing a model to predict the bankruptcy probability, it is necessary to consider the peculiarities of the enterprise’s production activity, the accuracy in creating the financial statements and many other factors, including the presence of company’s shares in circulation at the stock market. It is worthwhile to use a taxonomic analysis to make a comprehensive comparison of the enterprise financial state and to substantiate the final choice of the bankruptcy forecasting model.

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33

Klyuev, Dmitriy S., and Yulia V. Sokolova. "Singular integral equation for an electric dipole taking into account the finite metal conductivity from which it is made." Physics of Wave Processes and Radio Systems 24, no. 4 (January 16, 2022): 13–18. http://dx.doi.org/10.18469/1810-3189.2021.24.4.13-18.

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A singular integral equation for an electric dipole has been obtained, which makes it possible to take into account the finite conductivity of the metal from which it is made. The derivation of the singular integral equation is based on the application of the Greens function for free space, written in a cylindrical coordinate system, taking into account the absence of the dependence of the field on the azimuthal coordinate, on a point source located on the surface of an electric dipole. Methods for its solution are proposed. In contrast to the well-known mathematical models of an electric dipole, built in the approximation of an ideal conductor, the use of the singular integral equation obtained in this work makes it possible to take into account heat losses and calculate the efficiency.

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34

Sharma, O. P., and T. L. Butler. "Predictions of Endwall Losses and Secondary Flows in Axial Flow Turbine Cascades." Journal of Turbomachinery 109, no. 2 (April 1, 1987): 229–36. http://dx.doi.org/10.1115/1.3262089.

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This paper describes the development of a semi-empirical model for estimating end-wall losses. The model has been developed from improved understanding of complex endwall secondary flows, acquired through review of flow visualization and pressure loss data for axial flow turbomachine cascades. The flow visualization data together with detailed measurements of viscous flow development through cascades have permitted more realistic interpretation of the classical secondary flow theories for axial turbomachine cascades. The re-interpreted secondary flow theories together with integral boundary layer concepts are used to formulate a calculation procedure for predicting losses due to the endwall secondary flows. The proposed model is evaluated against data from published literature and improved agreement between the data and predictions is demonstrated.

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35

Hussein, Shaimaa A., Dhari Yousif Mahmood, and Ali Hussein Numan. "Loss reduction of transmission lines using PSO-based optimum performance of UPFC." Bulletin of Electrical Engineering and Informatics 12, no. 3 (June 1, 2023): 1237–47. http://dx.doi.org/10.11591/eei.v12i3.4559.

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Transmission line losses are one of the essential topics and issues in power systems research. Several methods and techniques have been used to reduce these losses, and one of these modern techniques is flexible alternating current transmission systems (FACTS). In this paper, one of the most important types of this technology, the unified power flow controller (UPFC), was used to reduce losses in the Iraqi national grid (ING) 400 kV. This paper presents an efficient method for minimizing losses of transmission lines in the ING system (400 kV) 46-bus approach. A particle swarm optimization (PSO)-based optimum proportional-integral (PI) controller with UPFC was proposed to obtain the optimal location of UPFC and optimum parameters of the PI controller to achieve the objective function of the research. MATLAB coded the algorithm. The Newton-Raphson method was employed to perform load flow analysis. The results showed that the best place for UPFC is buses (14-17) named BGE4 (Baghdad)-AMN4 (Baghdad), and the total active power and reactive power losses decreased from 727.4593 to 579.3874 MW and from 5155.9 to 3971.1 MVAR, respectively and also led to voltage regulation.

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36

Hueting, Roefie. "Economic Aspects of Environmental Accounting." Journal of Interdisciplinary Economics 2, no. 1 (April 1987): 55–71. http://dx.doi.org/10.1177/02601079x8700200105.

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This article explains that the environment forms an integral part of the economy. It then presents three applications of data on environmental losses and restoration: their integration in the System of National Accounts and their incorporation in cost-benefit analyses and economic models. Some arguments are given for the importance of doing so, notably in developing countries.

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37

Van Deventer, T. E., P. B. Katehi, and A. C. Cangellaris. "An integral equation method for the evaluation of conductor and dielectric losses in high-frequency interconnects." IEEE Transactions on Microwave Theory and Techniques 37, no. 12 (1989): 1964–72. http://dx.doi.org/10.1109/22.44109.

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38

Butyrin, Vasiliy V., Oleg G. Karapotkin, and Nikolay G. Platonovskiy. "Losses in the agro-food sector of Russia and the possibility of their reduction." Economy of agricultural and processing enterprises, no. 10 (2022): 16–24. http://dx.doi.org/10.31442/0235-2494-2022-0-10-16-24.

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The article deals with the problem of food losses and food waste at various stages of production and distribution chains as an integral part of global food and environmental problems, including its manifestation in the agro-industrial complex of Russia. The relevance of studying this topic is due to insufficient attention to it in our country from both the state and society. At the same time, food losses negatively affect the economy and the environment. The paper clarifies the concepts of “food losses” and “food waste”. Based on the analysis of research results and assessment of food losses, the causes of their occurrence are identified, as well as the main factors of the formation of food waste at the stages of marketing of food products are analyzed. Possible options for reducing losses and waste in the agro-food complex of the agro-industrial complex of Russia are proposed on the basis of: coordinating the work of government and business in this area; implementing investment projects to create the necessary infrastructure to avoid losses at the stages of production, transportation and storage of products; minimizing waste and loss of products with expiring shelf life due to technological and organizational solutions; attracting public attention and strengthening educational work in all layers of society, primarily among children and youth.

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39

Less, V. M., V. Y. Lyubchenko, and D. A. Pavlyuchenko. "Energy efficiency analysis of energy facilities using ranking methods." Power engineering: research, equipment, technology 25, no. 5 (January 12, 2024): 42–58. http://dx.doi.org/10.30724/1998-9903-2023-25-5-42-58.

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Анотація:

RELEVANCE. Increasing energy efficiency is one of the necessary conditions for modernizing the Russian economy. High energy intensity and energy efficiency analysis are due to the combined influence of a number of factors, both global and private. Thus, for electric grid organizations the problem of energy efficiency is a priority. Having at their disposal electrical grid facilities, including points of reception and transmission of electrical energy, electrical equipment and power transmission lines, electrical grid organizations incur huge losses caused by losses during the transmission of electrical energy, losses associated with the unaccounted share of electricity, as well as third-party factors. OBJECT. Conduct an analysis of the energy efficiency of an electric grid organization that has 10 branches. Form a hierarchy of energy efficiency indicators, determine the impact of each indicator on the integral indicator that reflects the energy efficiency of the facility. Conduct benchmarking, identify leaders and outsiders among power grid organizations. METHODS. To calculate the weight coefficients, the method of analysis of hierarchies in the classical and fuzzy formulations was used. Energy efficiency benchmarking was carried out by ranking power grid organizations according to the integral indicator of energy efficiency. RESULTS. A three-level hierarchy of energy efficiency indicators has been formed. A decision-making algorithm is presented when analyzing the energy efficiency of energy industry facilities. The weight coefficients of indicators and integral values of energy efficiency of organizations are calculated. The indicators that have the greatest impact on the overall efficiency of the facility were identified. A summary diagram of comparison of all branches has been formed, the most and least successful organizations have been identified. CONCLUSIONS. The analysis of energy efficiency, carried out using two methods of analysis of hierarchies, made it possible to identify the advantages and disadvantages of the classical representation of the method. Determination of leaders within the branch structure of the electric grid organization allows us to analyze the methods used to improve energy efficiency, as well as to introduce them in the future to less successful branches.

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40

Mvandaba, Vuyelwa, Denis Hughes, Evison Kapangaziwiri, Jean-Marc Mwenge Kahinda, and Nadia Oosthuizen. "Modelling of channel transmission loss processes in semi-arid catchments of southern Africa using the Pitman Model." Proceedings of the International Association of Hydrological Sciences 378 (May 29, 2018): 17–22. http://dx.doi.org/10.5194/piahs-378-17-2018.

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Abstract. Water availability is one of the major societal issues facing the world. The ability to understand and quantify the impact of key hydrological processes, on the availability of water resources, is therefore integral to ensuring equitable and sustainable resource management. Channel transmission losses are an “under-researched” hydrological process that affects resource availability in many semi-arid regions such as the Limpopo River Basin in southern Africa, where the loss processes amount to approximately 30 % of the water balance. To improve the understanding of these loss processes and test the capability of modelling routines, three approaches using the Pitman model are applied to selected alluvial aquifer environments. The three approaches are an explicit transmission loss function, the use of a wetland function to represent channel-floodplain storage exchanges and the use of a “dummy” reservoir to represent floodplain storage and evapotranspiration losses. Results indicate that all three approaches are able to simulate channel transmission losses with differing impacts on the regional flows. A determination of which method best represents the channel transmission losses process requires further testing in a study area that has reliable observed historical records.

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41

Jackson, D. J., K. L. Lee, P. M. Ligrani, and P. D. Johnson. "Transonic Aerodynamic Losses Due to Turbine Airfoil, Suction Surface Film Cooling." Journal of Turbomachinery 122, no. 2 (February 1, 1999): 317–26. http://dx.doi.org/10.1115/1.555455.

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The effects of suction surface film cooling on aerodynamic losses are investigated using an experimental apparatus designed especially for this purpose. A symmetric airfoil with the same transonic Mach number distribution on both sides is employed. Mach numbers range from 0.4 to 1.24 and match values on the suction surface of airfoils from operating aeroengines. Film cooling holes are located on one side of the airfoil near the passage throat where the free-stream Mach number is nominally 1.07. Round cylindrical and conical diffused film cooling hole configurations are investigated with density ratios from 0.8 to 1.3 over a range of blowing ratios, momentum flux ratios, and Mach number ratios. Also included are discharge coefficients, local and integrated total pressure losses, downstream kinetic energy distributions, Mach number profiles, and a correlation for integral aerodynamic losses as they depend upon film cooling parameters. The contributions of mixing and shock waves to total pressure losses are separated and quantified. These results show that losses due to shock waves vary with blowing ratio as shock wave strength changes. Aerodynamic loss magnitudes due to mixing vary significantly with film cooling hole geometry, blowing ratio, Mach number ratio, and (in some situations) density ratio. Integrated mixing losses from round cylindrical holes are three times higher than from conical diffused holes, when compared at the same blowing ratio. Such differences depend upon mixing losses just downstream of the airfoil, as well as turbulent diffusion of streamwise momentum normal to the airfoil symmetry plane. [S0889-504X(00)02202-9]

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42

Petrosyan, Tigran. "Two Approaches to the Study of Temperature Effect on the Dissipative Properties of Materials." Key Engineering Materials 906 (January 11, 2022): 69–76. http://dx.doi.org/10.4028/www.scientific.net/kem.906.69.

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In order to study the effect of temperature changes on the dissipative properties of materials, two approaches are used. The first approach implies introducing some temperature function under the sign of the integral in the heredity theory equation and simultaneously taking into account the dependence of the elastic modulus on temperature. As a result, based on experimental data on the thermal creep of soils, the expression for determining the hysteresis energy losses under the periodic voltage changes was obtained depending on temperature changes.According to the second approach, the expression for determining the hysteresis energy losses under isothermal conditions at different temperatures was obtained by introducing into the heredity theory equation an approximation of the experimental dependences of instantaneous deformation and temperature creep parameters for steel Kh18 N10T.

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43

Nickelson, Liudmila, Raimondas Pomarnacki, Tomyslav Sledevič, and Darius Plonis. "Method of Singular Integral Equations for Analysis of Strip Structures and Experimental Confirmation." Mathematics 9, no. 2 (January 11, 2021): 140. http://dx.doi.org/10.3390/math9020140.

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This paper presents a rigorous solution of the Helmholtz equation for regular waveguide structures with the finite sizes of all cross-section elements that may have an arbitrary shape. The solution is based on the theory of Singular Integral Equations (SIE). The SIE method proposed here is used to find a solution to differential equations with a point source. This fundamental solution of the equations is then applied in an integral representation of the general solution for our boundary problem. The integral representation always satisfies the differential equations derived from the Maxwell’s ones and has unknown functions μe and μh that are determined by the implementation of appropriate boundary conditions. The waveguide structures under consideration may contain homogeneous isotropic materials such as dielectrics, semiconductors, metals, and so forth. The proposed algorithm based on the SIE method also allows us to compute waveguide structures containing materials with high losses. The proposed solution allows us to satisfy all boundary conditions on the contour separating materials with different constitutive parameters and the condition at infinity for open structures as well as the wave equation. In our solution, the longitudinal components of the electric and magnetic fields are expressed in the integral form with the kernel consisting of an unknown function μe or μh and the Hankel function of the second kind. It is important to note that the above-mentioned integral representation is transformed into the Cauchy type integrals with the density function μe or μh at certain singular points of the contour of integration. The properties and values of these integrals are known under certain conditions. Contours that limit different materials of waveguide elements are divided into small segments. The number of segments can determine the accuracy of the solution of a problem. We assume for simplicity that the unknown functions μe and μh, which we are looking for, are located in the middle of each segment. After writing down the boundary conditions for the central point of every segment of all contours, we receive a well-conditioned algebraic system of linear equations, by solving which we will define functions μe and μh that correspond to these central points. Knowing the densities μe, μh, it is easy to calculate the dispersion characteristics of the structure as well as the electromagnetic (EM) field distributions inside and outside the structure. The comparison of our calculations by the SIE method with experimental data is also presented in this paper.

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44

Nickelson, Liudmila, Raimondas Pomarnacki, Tomyslav Sledevič, and Darius Plonis. "Method of Singular Integral Equations for Analysis of Strip Structures and Experimental Confirmation." Mathematics 9, no. 2 (January 11, 2021): 140. http://dx.doi.org/10.3390/math9020140.

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Анотація:

This paper presents a rigorous solution of the Helmholtz equation for regular waveguide structures with the finite sizes of all cross-section elements that may have an arbitrary shape. The solution is based on the theory of Singular Integral Equations (SIE). The SIE method proposed here is used to find a solution to differential equations with a point source. This fundamental solution of the equations is then applied in an integral representation of the general solution for our boundary problem. The integral representation always satisfies the differential equations derived from the Maxwell’s ones and has unknown functions μe and μh that are determined by the implementation of appropriate boundary conditions. The waveguide structures under consideration may contain homogeneous isotropic materials such as dielectrics, semiconductors, metals, and so forth. The proposed algorithm based on the SIE method also allows us to compute waveguide structures containing materials with high losses. The proposed solution allows us to satisfy all boundary conditions on the contour separating materials with different constitutive parameters and the condition at infinity for open structures as well as the wave equation. In our solution, the longitudinal components of the electric and magnetic fields are expressed in the integral form with the kernel consisting of an unknown function μe or μh and the Hankel function of the second kind. It is important to note that the above-mentioned integral representation is transformed into the Cauchy type integrals with the density function μe or μh at certain singular points of the contour of integration. The properties and values of these integrals are known under certain conditions. Contours that limit different materials of waveguide elements are divided into small segments. The number of segments can determine the accuracy of the solution of a problem. We assume for simplicity that the unknown functions μe and μh, which we are looking for, are located in the middle of each segment. After writing down the boundary conditions for the central point of every segment of all contours, we receive a well-conditioned algebraic system of linear equations, by solving which we will define functions μe and μh that correspond to these central points. Knowing the densities μe, μh, it is easy to calculate the dispersion characteristics of the structure as well as the electromagnetic (EM) field distributions inside and outside the structure. The comparison of our calculations by the SIE method with experimental data is also presented in this paper.

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45

Hamilton, Tracy P., and Henry F. Schaefer III. "The use of special coordinate axes in direct and semi-direct implementations of second-order perturbation theory, including the derivation of a horizontal recurrence relation." Canadian Journal of Chemistry 70, no. 2 (February 1, 1992): 416–20. http://dx.doi.org/10.1139/v92-060.

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A horizontal recurrence relation (HRR) is derived which may be used in the generation of two-electron repulsion integrals (ERIs). Also, special Cartesian coordinate axes may be used to reduce the number of intermediate terms. Heretofore, the use of local axis systems entailed rotations every time a shell quadruple of ERIs was computed. Recently, we pointed out the possibility of postponing the transformation using choices of Cartesian reference frames based on nuclear positions. In our pilot implementation of direct and semi-direct Møller–Plesset second-order perturbation theory (MP2) we construct the integrals in local coordinate systems and perform the back-transformation in the middle of the AO to MO integral transformation, rather than rotating the ERIs after the computation of each shell quadruple. The efficacy of this approach depends on whether the gains in ERI computation are greater than the losses incurred in transformation. Preliminary CPU profiles indicate that the increased time spent in rotating axes is quite small. Keywords: horizontal recurrence relation, second-order perturbation theory.

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46

Vidan, Cristian, Nicolae Jula, Martin Timmerman, and Robby Haelterman. "Detection Of High Voltage Lines Based On Analyzing Images Received From An UAV In Order To Detect Corona Discharge." International conference KNOWLEDGE-BASED ORGANIZATION 21, no. 3 (June 1, 2015): 760–63. http://dx.doi.org/10.1515/kbo-2015-0128.

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Abstract In the high voltage domain, the Corona discharge represents one of the most disturbing problems for the companies that transport electricity. Corona discharge is an electrical discharge brought on by the ionization of a fluid surrounding a conductor that is electrically energized. To combat this phenomenon it is necessary to keep high voltage power lines under surveillance and try to maintain losses at a reasonable value. The best manner to do this thing is by using a fixed-wing unmanned aircraft vehicle having on board the necessary sensors for detecting Corona discharge. In this paper we will focus on extracting and detecting high voltage lines from the images received from an UAV which will be analyzed using a number ofMATLAB functions. To detect lines into an image the Radon transformwill be used which is an integral transform that maps a function to its integrals over lines.

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47

Girshin, S. S., E. G. Andreeva, K. V. Khatsevskiy, V. M. Trotsenko, N. A. Melnikov, E. V. Petrova, and V. N. Goryunov. "Power management of variable capacitors in electrical grid systems according to the criterion of mini-mum energy loss." iPolytech Journal 25, no. 6 (January 11, 2022): 741–52. http://dx.doi.org/10.21285/1814-3520-2021-6-741-752.

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The aim is to manage the transmitted reactive power in electrical grids using variable capacitor batteries according to the criterion of minimum energy loss under different annual reactive load schedules and different numbers of variable capacitor sections. The main theoretical relations were obtained by the methods of mathematical modelling and integral calculus using the theory of optimal control. The influence of the power and number of sections in a capacitor battery on energy losses in the grid was estimated using computational experiments. Dependencies for energy losses in a capacitor battery, as well as for reducing energy losses in the grid, were obtained. These expressions are valid for linearized load schedules. It is shown that the dependences of energy losses in a capacitor battery and the reduction of losses in the grid on the section power have inflection points and pass through a maximum. The presence of inflection points is associated with a change in the number of capacitor sections operating throughout the year. The presence of a maximum is explained by the fact that, with an increase in the power of the capacitor battery, its operating time decreases under the complete number of variable sections. It is established that the batteries of static capacitors with two variable sections can reduce energy losses when transmitting reactive power by over 90%. For three- and four-section static capacitors, the loss reduction is close to 100%. The reduction in energy losses increases when approaching maximal levels of annual reactive load. Energy losses in electrical grid systems can be reduced by capacitor batteries with no more than three or four variable sections. In most cases, this can be achieved by two-section capacitor batteries.

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48

Kelz, Andreas. "Antarctica – a case for 3D-spectroscopy." Proceedings of the International Astronomical Union 2, no. 14 (August 2006): 707–8. http://dx.doi.org/10.1017/s1743921307012355.

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DS or Integral-Field Spectroscopy (IFS) provides multiple spectra for each point of a 2-D field, rather than along a narrow, 1-D spectrograph slit only. Therefore, IFS does not require very accurate telescope pointing, nor do pre-assumptions about slit or aperture sizes have to be made. It avoids any ‘slit-losses’ due to seeing or atmospheric dispersion, which eliminates the need for any parallactic alignment or a dispersion compensator (see Fig. 1).

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49

Dunaev, Mihail, and Sarfaroz Dovudov. "SIMULATION OF A CLOSED SYSTEM OF A DC ELECTRIC DRIVE WITH A WIDTH-PULSE CONVERTER." Bulletin of the Angarsk State Technical University 1, no. 15 (January 12, 2022): 42–47. http://dx.doi.org/10.36629/2686-777x-2021-1-15-42-47.

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This article investigates the regulation of the angular speed of an electric drive (ED) with a pulse-width converter (PWC) and a direct current motor (DC motor) of independent excitation (NV) when controlled in a closed-loop system. A proportional-integral (PI) -regulator was used as a regulator of the angular velocity. To analyze the processes in the closed-loop SHIP-DPT system, the methods of simulation are used. The principle of operation of an electric drive with control from a PWM is described. Developed and modeled EP circuits with PWM in the Matlab environment using blocks from the Simulink / SimPowerSystem library. A model block has been modeled that calculates the static and dynamic power losses of the PWP IGBT. To calculate the static and dynamic losses, the method of approximating the loss graphs was used. The obtained mathematical dependences describe quite accurately the graphs of the power losses of the IGBT transistor. It is shown that when using a PI-controller, the angular speed of the electric drive is set according to a given speed reference signal.

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50

Ojo, Ebenezer, Adesola Adewuyi, Josiah Fanifosi, Chinedu Ezugwu, and Yinka Ogunkeyede. "A Microcontroller Based Proportional Integral Derivative Controller for Yam Tuber Storage Chamber Temperature and Humidity Control." Nigerian Journal of Engineering 30, no. 2 (2023): 59. http://dx.doi.org/10.5455/nje.2023.30.02.09.

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Adequate and suitable controlled atmosphere plays an important role in post-harvest yam tuber storage environment for sustaining the quality and quantity of yam tuber especially in a reputable country that produces largest quantities of yam in the world. The effect of post-harvest loss is caused due to lack of appropriate storage systems and these had been the most common problem faced by small-holder yam farmers. In order to avoid post-harvest losses and food wastages due to poor atmospheric condition in West Africa, this paper proposed a microcontroller based Proportional Integral Derivative (PID) controller for controlling the temperature and humidity of yam tuber post-harvest storage. The due technique would maintain a relatively constant temperature and humidity in a storage chamber so as to minimized high level of yam postharvest losses that has become a serious economic and food security threat in West Africa. Some mathematical equations were formulated based on temperature and humidity storage chamber models using heat and energy balance principles. The models were designed using Proteus tools and simulated in Simulink form. The parameters of PID controller were tuned with Ziegler Nichols to achieve a desirable steady state response. The system performances were evaluated in settling time, temperature and humidity set point tracking. The performance metrics were compared with existing technique of Fuzzy Logic Controller (FLC). The sensitivity of the results justified that proposed technique gave a better performance in terms of decreased in settling time, temperature and humidity.

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