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G. Zaleskis

Abstract

Integration of renewable energy sources and the improvement of the technological base may not only reduce the consumption of fossil fuel and environmental load, but also ensure the power supply in regions with difficult fuel delivery or power failures. The main goal of the research is to develop the methodology of evaluation of the wind turbine economic efficiency. The research has demonstrated that the electricity produced from renewable sources may be much more expensive than the electricity purchased from the conventional grid.

Open access

A. Mutule, J. Teremranova and N. Antoskovs

., Gugliermetti, F., & Bisegna, F. (2015). A multilevel method to assess and design the renovation and integration of Smart Cities. Sustainable Cities and Society , 15 , 105–119. https://doi.org/10.1016/j.scs.2014.12.002 15. Girardi, P., & Temporelli, A. (2017). Smartainability: A methodology for assessing the sustainability of the smart city. Energy Procedia, 111 , 810–816, ScienceDirect. 8th International Conference on Sustainability in Energy and Buildings, SEB-16, 11–13 September, 2016, Turin, Italy. 16. BSI. (n.d.). PD 8101 Smart city planning guidelines

Open access

J. Beriņš, J. Beriņš, J. Kalnačs and A. Kalnačs

Abstract

The present article deals with one of the alternative forms of energy – sea wave energy potential in the Latvian Exclusice Economic Zone (EEZ). Results have been achieved using a new method – VEVPP. Calculations have been performed using the data on wave parameters over the past five years (2010–2014). We have also considered wave energy potential in the Gulf of Riga. The conclusions have been drawn on the recommended methodology for the sea wave potential and power calculations for wave-power plant pre-design stage.

Open access

A. Serebryakov, E. Kamolins, K. Gulbis and K. Sejejs

Abstract

The authors consider several tens of rotor tooth and slot profiles for the inductor electric machine in order to gain the maximum EMF of the armature winding at the minimum of highest harmonics, owing to which the specific power and efficiency of the machine can be raised.

The research considers usage of analytical methodology and finite element method (FEM), where the latter includes magnetic saturation and actual magnetic field line distribution.

The main data of both calculations are summarised in the results of the study. From the obtained results, it can be concluded that, in most cases, the analytical method is not applicable to the qualitative determination of the highest harmonic content of the EMF, since the plane of the magnetic field lines does not close in parallel and their distribution is directly related to the configuration of the teeth zone.

The possibility of using the inductor generators for direct connection to the grid is demonstrated in the study.

Open access

R. Grunvalds, A. Ciekurs, J. Porins and A. Supe

Abstract

In the research, measurements of polarisation mode dispersion of two OPGWs (optical ground wire transmission lines), in total four fibres, have been carried out, and the expected lifetime of the infrastructure has been assessed on the basis of these measurements. The cables under consideration were installed in 1995 and 2011, respectively. Measurements have shown that polarisation mode dispersion values for cable installed in 1995 are four times higher than that for cable installed in 2011, which could mainly be explained by technological differences in fibre production and lower fibre polarisation mode dispersion requirements in 1995 due to lack of high-speed (over 10 Gbit/s) optical transmission systems. The calculation methodology of non-refusal work and refusal probabilities, using the measured polarisation mode dispersion parameters, is proposed in the paper. Based on reliability calculations, the expected lifetime is then predicted, showing that all measured fibres most likely will be operational within minimum theoretical service life of 25 years accepted by the industry.

Open access

E. Lipenbergs, Vj. Bobrovs and G. Ivanovs

Abstract

To ensure that end-users and consumers have access to comprehensive, comparable and user-friendly information regarding the Internet access service quality, it is necessary to implement and regularly renew a set of legislative regulatory acts and to provide monitoring of the quality of Internet access services regarding the current European Regulatory Framework. The actual situation regarding the quality of service monitoring solutions in different European countries depends on national regulatory initiatives and public awareness. The service monitoring solutions are implemented using different measurement methodologies and tools. The paper investigates the practical implementations for developing a harmonising approach to quality monitoring in order to obtain objective information on the quality of Internet access services on mobile networks.

Open access

Z. Budjko and V. Zēbergs

Influence of Changes in Hot Water Consumption on the DHS Development

The methodology proposed in the paper is based on the concept of Energy Efficiency Uninterrupted Development Cycle (EEUDC). The goal of the authors was to clarify how the district heating system (DHS) development is affected by the heat consumption. The primary emphasis was given to the hot water consumption, with its noticeable daily fluctuations as well as changes caused by those in the inhabitants' way of life. The methodology, which is in good agreement with the ideology of advanced management of DHS development, employs the ISO 14000 series of standards (widely applied in the sphere of environment management). In the work, experimental results are presented that have been obtained through monitoring the hot water consumption. The results evidence that this consumption and its usage indices correspond to the level achieved by Western (in particular, North-European) countries. This circumstance changes considerably the input data for calculation of DHS elements, making it possible to work out appropriate measures in order to improve the DHS efficiency through step-by-step replacement of the elements with high energy loss.

Open access

M. Laicāns, I. Puķīte, I. Geipele, N. Zeltins and A. Greķis

Abstract

Literature review aims at examining various scientific articles on the accounting methods of individual heat consumption and heat cost allocation.

Nowadays, accounting methods of heat consumption and heat cost allocation in multi-apartment buildings are a topical issue. Heat and water supply is one of the key services provided to residential buildings and their residents. Residents appreciate solutions that allow them consume as much heat as they need and are able to pay, but on condition that the calculation methodology is understandable and easy to perceive.

Directive 2010/31/EU on the Energy Performance of Buildings adopted by the European Parliament and the Council (Directive 2010/31/EU of the European Parliament and of the Council, 2010) stipulates that owners or te-nants of buildings shall be provided with the information on energy efficiency measures, their goals and objectives, cost effective ways to improve the energy performance of a particular building and, where appropriate, in the case of available financial instruments to improve the energy performance of a particular building.

The aim of the research is to perform literature analysis using topical articles on the accounting methods of individual heat consumption and heat cost allocation, which are published in the Web of Science and Scopus scientific databases, by analysing and comparing the published results.

Open access

A. Obushevs, I. Oleinikova and A. Mutule

Abstract

The operational conditions of new networks dictate new requirements for the transmission planning, which would include the electricity market figures and a sizable involvement of renewable generation. This paper focuses on the transmission expansion planning techniques based on the calculations of optimal power flows and on the concept of development planning and sustainability. A description is given for the mathematical model of calculations and analysis of transmission system. The results have shown that the Baltic transmission system infrastructure can successfully be analyzed based on the proposed methodology and developed mathematical model

Open access

B. Aliyarov, A. Mergalimova and U. Zhalmagambetova

Abstract

The theoretical and practical introduction of this kind of firing boiler units in coal thermal power plants is considered in the article. The results of an experimental study of three types of coals are presented in order to obtain the required gaseous fuel.

The aim of the study is to develop a new, economically and ecologically more acceptable method for firing boilers at thermal power plants, which is able to exclude the use of expensive and inconvenient fuel oil.

The tasks of the experiment are to develop a technological scheme of kindling of boilers at thermal power plants, using as a type of ignition fuel volatile combustible substances released during the heating of coal, and to investigate three types of coal for the suitability of obtaining gaseous fuels, in sufficient volume and with the required heat of combustion.

The research methods include the analysis of technical and scientific-methodological literature on the problem of the present study, the study of the experience of scientists of other countries, the full-scale experiment on the production of volatile combustible substances.

During the full-scale experiment, the coal of 3 fields of Kazakhstan has been studied: Shubarkul, Maikuben and Saryadyr. The analysis has been performed and the choice of the most convenient technology for boiler kindling and maintenance of steady burning of the torch has been made according to the proposed method, as well as the corresponding technological scheme has been developed.

As a result of the experiment, it can be stated that from coal in the process of its heating (without access to oxygen), it is possible to obtain a sufficient amount of combustible volatile substances. The released gaseous fuel has the necessary parameters and is quite capable of replacing an expensive fuel oil. The resulting gaseous fuel is quite convenient to use and environmentally cleaner. The piloting scheme developed as a result of the experiment can be introduced in pulverized-coal thermal power plants, as a result of which they become single-fuel.