Faculty of Mechanical Engineering

Parent Organisation
City
Skopje

Filters

Settings

Now showing 1 - 10 of 449
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Improving Energy Efficiency of the Hydraulic Power Systems in Heavy Machinery
    (University Library in Kragujevac, 2020)
    Anastasovski, Dejvid
    ;
    ;
    ;
    Rath, Gerhard
    ;
    The main goal of the research done in this paper is to examine possible improvements in energy efficiency of the hydraulic power systems and with this lower gas emission from working machinery. It is here given a brief explanation of the existing hydraulic systems putting special attention on a hydraulic system with separate meter-in and separate meter-out (SMISMO). While the aim of this research is to improve the hydraulic energy efficiency mainly using the SMISMO system, additional research on using those systems for simultaneous speed and pressure control of the cylinders is also observed. The results obtained through experimental studies will be used to further improve the hydraulic system. Further upgrade of this system is to design automated SCADA system for improved data acquisition and control the valves in servo systems.</jats:p>
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Energy flexibility scenarios for North Macedonia
    (International Association for Hydro-Environment Engineering and Research (IAHR), 2022)
    ;
    ;
    ;
    The Paris Agreement signed in 2015, unites nearly 200 countries on the goal of limiting global warming and lowering carbon emissions. The goal of lowering carbon emissions can mainly be achieved by lowering fossil fuels within the energy sector since their use in electricity generation is a significant contributor to greenhouse gas emissions. This is why European countries, as well as North Macedonia, are planning to reduce the amount of climate-damaging fossil-fueled power plants, but to cover electricity demand, the share of renewable energies (in North Macedonia mostly wind and solar energy, here addressed as intermittent renewable energy sources - IRES) within their power systems must be increased. Changing power systems and including higher shares of IRES will increase imbalances and thus the need for flexibility (refers to means able to balance electricity supply and demand). Imbalances have always occurred in power systems, resulting from various reasons, and power systems are able to react with flexibility. Considered options, categorized into four kinds of flexibility (dispatchable generation, demand side management, increased interconnection, and energy storage), all offer possibilities to balance the systems by different approaches. Although all providing individual advantages, hydropower, especially pumped storage hydropower, was identified in this paper to be a very flexible, diverse option and a technology capable of meeting flexibility challenges set by the increase of IRES. The need for flexibility in the hydropower production could be improved using variable-speed turbines instead of multiple start-stops depending on the grid demand.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Two applications of Grunsky coefficients in the theory of univalent functions
    (Universitatea Sapientia din municipiul Cluj-Napoca, 2023-12-01)
    Obradović, Milutin
    ;
    <jats:title>Abstract</jats:title> <jats:p>Let <jats:italic>S</jats:italic> denote the class of functions f which are analytic and univalent in the unit disk 𝔻 = {z : |z| < 1} and normalized with <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/j_ausm-2023-0017_eq_001.png" /> <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:mrow> <m:mtext>f</m:mtext> <m:mrow> <m:mo>(</m:mo> <m:mtext>z</m:mtext> <m:mo>)</m:mo> </m:mrow> <m:mo>=</m:mo> <m:mtext>z</m:mtext> <m:mo>+</m:mo> <m:msubsup> <m:mo>∑</m:mo> <m:mrow> <m:mtext>n</m:mtext> <m:mo>=</m:mo> <m:mn>2</m:mn> </m:mrow> <m:mo>∞</m:mo> </m:msubsup> <m:mrow> <m:msub> <m:mrow> <m:mi>α</m:mi> </m:mrow> <m:mtext>n</m:mtext> </m:msub> <m:msup> <m:mrow> <m:mtext>z</m:mtext> </m:mrow> <m:mtext>n</m:mtext> </m:msup> </m:mrow> </m:mrow> </m:math> <jats:tex-math>{\rm{f}}\left( {\rm{z}} \right) = {\rm{z}} + \sum\nolimits_{{\rm{n = 2}}}^\infty {{\alpha _{\rm{n}}}{{\rm{z}}^{\rm{n}}}}</jats:tex-math> </jats:alternatives> </jats:inline-formula>. Using a method based on Grusky coefficients we study two problems over the class <jats:italic>S</jats:italic>: estimate of the fourth logarithmic coefficient and upper bound of the coefficient difference |α<jats:sub>5</jats:sub>| − |α<jats:sub>4</jats:sub>|.</jats:p>
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Understanding and application of quality costs in automotive manufacturing companies in North Macedonia: empirical study
    (Emerald, 2022-11-04)
    Velkoska, Cvetanka
    ;
    <jats:sec><jats:title content-type="abstract-subheading">Purpose</jats:title><jats:p>This study aims at presenting deeper insights regarding the understanding and application of the quality costs (CoQ) in the automotive manufacturing industry. The empirical research included three general determinants: reasons for, difficulties during and benefits from implementing quality costs, as well as two specific determinants: measuring and evaluating quality cost elements.</jats:p></jats:sec><jats:sec><jats:title content-type="abstract-subheading">Design/methodology/approach</jats:title><jats:p>The empirical research methodology employs the expert evaluation method – the Delphi method, using a survey questionnaire comprising a total of 200 questions, and answered by 9 companies.</jats:p></jats:sec><jats:sec><jats:title content-type="abstract-subheading">Findings</jats:title><jats:p>The survey results showed that companies do recognize the reasons for implementing quality costs as a need arising from the quality management standards, the lack of knowledge of quality costs by employees and management as the biggest difficulty while the biggest benefit includes the quality costs enhance the company competitiveness. The costs competence and qualification, the quality management system costs, the costs for improvement, the production control costs, the input control costs, the new measuring and control equipment calibration costs, the costs related to scrap, repairs and product finishing are the most significant elements of the quality costs.</jats:p></jats:sec><jats:sec><jats:title content-type="abstract-subheading">Research limitations/implications</jats:title><jats:p>This study is limited by the small number of surveyed companies from the automotive cluster.</jats:p></jats:sec><jats:sec><jats:title content-type="abstract-subheading">Practical implications</jats:title><jats:p>The proposed quality costs model provides to the management to conceive CoQ elements as possible drivers in the improvement process of product quality. The structure and the nature of the CoQ elements is expected to advance the process of detailing the quality costs elements.</jats:p></jats:sec><jats:sec><jats:title content-type="abstract-subheading">Originality/value</jats:title><jats:p>The novelty of this paper refers to development of a generic quality cost model, whose relevance is confirmed by the structuring of the model with elements published in literature and validating in research companies.</jats:p></jats:sec>
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Mathematical terminology: On the names of fractions in the Macedonian language
    (Union of Mathematicians of Macedonia, 2016)
    Celakoska-Jordanova, Vesna
    ;
    In this note we discuss the question of the names of fractions in the Macedonian language and explain our position in using а consistent system for generating nouns that denotes fractions, a system that is unambiguous and clear, unique and complete.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Canonical commutative ternary groupoids
    (Hikari, Ltd., 2017)
    Celakoska-Jordanova, Vesna
    ;
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    ENERGY HARVESTING USING PIEZOELECTRIC CERAMICS INCORPORATED IN A SHOE-SOL
    (University Ss. Cyril and Methodius in Skopje, 2020)
    Grazhdani, Franka
    ;
    Anachkova, Maja
    ;