scholarly journals Another Look at the Ehrenfest Urn Via Electric Networks

1994 ◽  
Vol 26 (3) ◽  
pp. 820-824 ◽  
Author(s):  
José Luis Palacios

Using the electric network approach, we give closed-form formulas for the expected hitting times in the Ehrenfest urn model.

1994 ◽  
Vol 26 (03) ◽  
pp. 820-824 ◽  
Author(s):  
José Luis Palacios

Using the electric network approach, we give closed-form formulas for the expected hitting times in the Ehrenfest urn model.


1993 ◽  
Vol 25 (02) ◽  
pp. 472-476 ◽  
Author(s):  
José Luis Palacios

Using the electric network approach, we give very simple derivations for the expected first passage from the origin to the opposite vertex in the d-cube (i.e. the Ehrenfest urn model) and the Platonic graphs.


1993 ◽  
Vol 25 (2) ◽  
pp. 472-476 ◽  
Author(s):  
José Luis Palacios

Using the electric network approach, we give very simple derivations for the expected first passage from the origin to the opposite vertex in thed-cube (i.e. the Ehrenfest urn model) and the Platonic graphs.


2020 ◽  
Vol 14 (1) ◽  
pp. 48-54
Author(s):  
D. Ostrenko ◽  

Emergency modes in electrical networks, arising for various reasons, lead to a break in the transmission of electrical energy on the way from the generating facility to the consumer. In most cases, such time breaks are unacceptable (the degree depends on the class of the consumer). Therefore, an effective solution is to both deal with the consequences, use emergency input of the reserve, and prevent these emergency situations by predicting events in the electric network. After analyzing the source [1], it was concluded that there are several methods for performing the forecast of emergency situations in electric networks. It can be: technical analysis, operational data processing (or online analytical processing), nonlinear regression methods. However, it is neural networks that have received the greatest application for solving these tasks. In this paper, we analyze existing neural networks used to predict processes in electrical systems, analyze the learning algorithm, and propose a new method for using neural networks to predict in electrical networks. Prognostication in electrical engineering plays a key role in shaping the balance of electricity in the grid, influencing the choice of mode parameters and estimated electrical loads. The balance of generation of electricity is the basis of technological stability of the energy system, its violation affects the quality of electricity (there are frequency and voltage jumps in the network), which reduces the efficiency of the equipment. Also, the correct forecast allows to ensure the optimal load distribution between the objects of the grid. According to the experience of [2], different methods are usually used for forecasting electricity consumption and building customer profiles, usually based on the analysis of the time dynamics of electricity consumption and its factors, the identification of statistical relationships between features and the construction of models.


Author(s):  
Maksym Hrebenichenko

At optimization of development of electric networks of power systems voltage and a configuration of networks are chosen, the order of construction of objects of electric networks is established. The criterion of optimality in optimization is the sum of dynamic consolidated costs for all network elements. The decision must take into account the dynamics of development of power systems networks, requirements for reliability and quality of power supply, capacity constraints on power lines and transformer substations.


2021 ◽  
Vol 8 ◽  
Author(s):  
Dayong Wang ◽  
Yujun Yang

The resistance distance between any two vertices of a connected graph is defined as the net effective resistance between them in the electrical network constructed from the graph by replacing each edge with a unit resistor. In this article, using electric network approach and combinatorial approach, we derive exact expression for resistance distances between any two vertices of polyacene graphs.


2021 ◽  
Vol 1 (1) ◽  
pp. 35-43
Author(s):  
Mukhammadzhon М. KAMOLOV ◽  
◽  
Sagid A. АBDULKERIMOV ◽  
Khurshed B. NAZIROV ◽  
Shokhin D. DZHURAEV ◽  
...  

During the operation of 0.4 kV electric networks, asymmetry of currents and voltages is unavoidable. As is known, unbalanced operation of 0.4 kV networks is stemming from nonuniform distribution of loads between the phases. This results in that a fundamental frequency zero-sequence current will flow through the neutral conductor in a four-wire three-phase electric network. On the other hand, during balanced operation of a four-wire electric network containing loads with a nonlinear volt-ampere characteristic, higher harmonic currents multiple to three are summed in the neutral conductor. Therefore, it is of relevance to analyze unbalanced operating conditions of a four-wire electric network containing loads with a nonlinear volt-ampere characteristic. The article presents the characteristics of a municipal load for analyzing unbalanced/nonsinusoidal conditions of its operation. For carrying out full-valued assessment of unbalanced operating conditions of a four-wire electric network, a simulation model of a 0.4 kV network section containing a nonsinusoidal load is developed. It is shown that during unbalanced operation of an electric network containing electric loads with a nonlinear volt-ampere characteristic it is recommended to take into account zero-sequence current higher harmonic components that are not multiple to three. An algorithm for calculating the neutral conductor current harmonic component for determining the cable temperature rating is developed.


2019 ◽  
Vol 140 ◽  
pp. 07003 ◽  
Author(s):  
Tamara Pudkova ◽  
Alexey Bardanov

The existing approach to electricity metering, which underlies the formation of payment for consumed electricity, has a significant drawback. It can be correctly used in systems with a sinusoidal symmetrical mode, but needs to be improved in other network modes. The article defines indicators that numerically reflect the effect of distortions on the modes of distribution electric networks, as well as indicators that take into account consumed inactive power (by analogy with reactive power in a sinusoidal mode) when paying electricity bills to an electricity supplier. The proposed principles of electricity consumption metering includes the influence of such indicators as the spectral composition of voltage and current, the ratio of linear and nonlinear loads of consumers, as well as the influence of the topology of the electric network.


Author(s):  
M. I. Fursanov ◽  
A. A. Zalotoy

The method of calculation of the steady-state mode of the open city distribution electric network with small generation sources is offered. It is shown that the city electric network consists of passive and active physical elements. Passive elements include power transformers and linear regulators, overhead and cable power lines, current-limiting reactors, etc. Active elements of networks are power sources (transformer inputs of low voltage of feeding substations and distributed small generation sources) and loads, mathematical models of which can be various. Power sources in urban distribution networks of 10 kV and below are classified by type and power and can be of two kinds, viz. power feeding centers of the network and small generation sources. Consumer loads are modeled by current sources connected to network nodes. The parameters of the current sources are usually graphs of the change of the module of the actual current value and the power factor in time. The values of these parameters in single-line substitution schemes of 6–10 kV distribution networks with isolated neutral are assumed to be average for three phases. The power centers are transformer inputs of low voltage power substations of the main electric networks of 35 kV and above, equipped with digital devices of the account of the electric power connected to the automated system of control and accounting of power resources. The developed technique allows receiving the refined balanced calculation model of the steady mode of the open city network for the set time of the daily schedule. It includes the sequential distribution of the specified power of each network power supply between its loads, followed by clarification of flows and power losses in the sections, as well as voltages and actual loads in the nodes of the scheme by the overlay method.


2021 ◽  
Vol 10 (1) ◽  
pp. 46-54
Author(s):  
Alexander Ivanovich Sidorov ◽  
Saidjon Tavarov

The article is devoted to the actual problem of how to improve the reliability of the urban electric network. Based on the statistical analysis of the breakdown of electrical equipment in urban distribution networks in Dushanbe for the periods of 2017-2018 and for the reasons of damage leading to these emergency outages, the factors that affect the distribution of damage leading to emergency outages are identified. Taking into account the identified factors, a power consumption forecasting system is proposed that takes into account the local conditions of the city of Dushanbe. it allows us to suggest a way to control the operating parameters of the electric network, thereby increasing the reliability of the city's electric network in Dushanbe based on the recommendation of power consumption standards. Implementation of the control of the proposed method for improving the reliability of power supply to the urban electric network is proposed on the basis of the functionality of modern smart electricity metering using the control algorithm. To implement the control algorithm, schematic design for receiving and transmitting information from smart power metering to the data collection centre is proposed.


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