Use of active elements for providing suitable voltage profiles and prevent overloads in radial distribution networksMarko Vodenik
, Matej Pintarič
, Gorazd Štumberger
, 2022, izvirni znanstveni članek
Opis: The article deals with the issue of providing suitable voltage profiles and preventing congestion of network elements in distribution networks. Active network elements and network users’ energy flexibility services are used to provide a suitable voltage profile and prevent congestion in distribution networks. The discussed active network elements include a transformer with on-load tap changer, reactive power compensation devices, energy storage systems, distributed energy resources, and network users’ energy flexibility services, where the active consumers adjust their consumption, production and storage of energy. Based on the Backward Forward Sweep load flow computation method, the case studies are performed for the discussed low voltage distribution network, where the measurement results were available. The case studies for preventing overload of the distribution transformer are performed using a battery energy storage system and network users’ energy flexibility services. The case studies for providing suitable voltage profiles are performed using all listed active elements and a combination of different active elements. In addition, to provide suitable voltage profiles, the existing conductors are replaced with conductors of a larger cross-section. Technically acceptable solutions that can provide a suitable voltage profile and prevent the overloading of network elements in the most demanding operating conditions are presented in this article.
Ključne besede: voltage profile, radial distribution network, load flow calculations, active network elements, energy flexibility
Objavljeno v DKUM: 30.10.2023; Ogledov: 121; Prenosov: 3
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Part-time jobs: opportunity or obstacle? : case of the Moravian-Silesian RegionŠárka Čemerková
, Irena Šebestová
, Roman Šperka
, 2018, pregledni znanstveni članek
Opis: Background and Purpose: Part-time employment could be seen as a modern form of employment or a type of innovative organizational change. The average share of part-time jobs in the Czech Republic in the observed period of 2004-2016 was 3.9 % according to the OECD, in comparison to the average OECD value of 16.6%. The main question to arise was, are there any regional differences? The presented conclusions are based on a regional study in the Moravian-Silesian Region (MSR) in the Czech Republic where the median value of part- time jobs is 10%. The main goal is to evaluate the regional level of part-time job offers and identify the main opportunities and obstacles which cause the low number of these job positions.
Design/Methodology/Approach: The paper is based on a quantitative study using a questionnaire-based survey, comprising 215 respondents – owners of small and medium-sized enterprises (SMEs) in the Moravian-Silesian Re- gion in the Czech Republic. The survey consists of 16 questions in three main areas: (i) Entrepreneurial motivation (1 item), (ii) External factors – Labour market problems (4 items), and (iii) Internal factors. Secondary information such as the results of earlier studies and regional government websites were used for data results comparison. All variables are compared in the context of the branch of business, number of employees, turnover, and age. Finally, a factor analysis was used to find the main way how to improve part-time job offers.
Results: The variety of businesses and different regional locations opens up space for discussion regarding part- time job support. A factor analysis found five significant issues, which could affect local labour market and company behaviour.
Conclusion: The added value of the paper can be seen in the factor identification, where internal willingness to sup- port part-time employment and qualification growth as organizational change must be in first place.
Ključne besede: flexibility, Moravian Silesian Region, part-time employment, SME
Objavljeno v DKUM: 10.10.2018; Ogledov: 827; Prenosov: 134
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Flexicurity or flexicarity? : a Portuguese overviewNoemia Bessa Vilela
, José Caramelo Gomes
, Natacha Silva
, 2016, izvirni znanstveni članek
Opis: Due to the increasing competition on the labour market, the search for new approaches to labour legislations led to the creation and adoption, in some countries, of so called “flexicurity”. “Flexicurity” became top of the list in the policy agenda in the European Union, but there is doubt that such an agenda for encompassing labour market reform providing not employment. As sources are used “flexicurity” models, in countries where it has already been successfully implemented, as well as Eurostat data, information made available by the European Commission, as well as doctrinal and research papers. Portuguese jurisdiction is considered by national legal doctrine as a closed model. Heavy regulation and constitutional constraints drive an almost unanimous rejection of the possibility to introduce the concept at national level. This article's goal is to discuss the ways the concept could be introduced in the Portuguese jurisdiction. Would the model effectively create security, or would it result in precarity?
Ključne besede: labour, flexicurity, security, flexibility, employment
Objavljeno v DKUM: 02.08.2018; Ogledov: 952; Prenosov: 64
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Multi-objective synthesis of company’s supply-networks based on integration of renewable resourcesAnnamaria Vujanović
, 2017, doktorska disertacija
Opis: The aim of this doctoral dissertation was to develop a general methodology for sustainable integration of company's supply networks into nearby regional networks by i) integrating renewables, thereby increasing company's energy self-sufficiency, ii) by performing multi-objective synthesis in order to obtain economically efficient and yet environmentally benign or even unburdening solutions, and iii) to perform dynamic and stochastic synthesis under uncertainties in dynamically changing market conditions in order to obtain more reliable and realistic solutions. The research work is directly interlinked with a large-scale European meat producing company Perutnina Ptuj d.d., which is located in the heart of Slovenia.
The aim of the first part was to integrate renewables into companies’ supply-networks at regional level in order to maximize the self-sufficiencies of their energy supplies. This concerns companies’ activities from the use of natural resources to supplying their final products to the customers being interlinked with their regional networks. A Mixed-Integer Linear Programming (MILP) model has been developed for the integration of both the companies’ and surrounding regional supply-networks and the utilization of different types of renewables as sources for the companies’ energy supplies. The potential renewable energy sources, which are located within companies surrounding region are solar, biomass, organic and animal wastes. The result indicates that by sufficient integration of renewables into companies’ supply networks, profitable and yet energy self-sufficient solutions can be obtained.
The second part presents the multi-objective synthesis of a company’s supply-network by integrating renewables and accounting for several environmental footprints. A previously developed model for achieving energy self-sufficiency by integrating renewables into companies’ supply-networks has been extended for the evaluation of environmental impacts, such as energy, carbon, nitrogen, and water footprints. The achievement of an energy self-sufficient supply-network has been considered whilst significantly reducing environmental impacts. Direct (burdening) and indirect (unburdening) effects that form total effects on the environment are considered for the evaluation of environmental footprints. This approach identifies those alternative energy production technologies that are more profitable and environmentally more benign with significant unburdening capabilities. The results showed significant unburdening of the environment in terms of carbon and nitrogen footprints; however, higher burdening in terms of the water footprint.
The third part presents a multi-objective MILP synthesis of a dynamic supply-network under uncertainty applied to the company. The previously-developed multi-objective model for achieving energy self-sufficiency by integrating renewables into companies’ supply-networks has now been extended to account for the dynamic consideration of variable supply and demand over the year, for uncertainties related to products’ demand and sun radiation, and for multi-objective optimisation, in order to obtain the most sustainable company’s supply-network. The sustainable synthesis of a company’s network is performed regarding the integration of the renewables such as biomass and other wastes, and solar energy. The obtained solutions are those reflecting maximal profit, reflecting constantly-changing dynamic market conditions, accounting for several uncertain parameters, and protecting the environment.
Ključne besede: Company's supply network, Renewables, Environmental Impacts, Dynamic synthesis, Flexibility, Multi-objective optimisation, Uncertainty
Objavljeno v DKUM: 21.07.2017; Ogledov: 1460; Prenosov: 162
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The role of tipping in reducing labour costs : case of sector retail petroleum productsAndrej Raspor
, Gozdana Miglič
, Goran Vukovič
, Blaž Rodič
, 2014, izvirni znanstveni članek
Opis: The purpose of this paper was to determine whether tipping could reduce labour costs in the petroleum products retail sector. The research we present was designed on the basis of survey results gathered from Slovenian petrol stations in 2009 and 2010. We have identified the following factors in the tipping process: job satisfaction, flexibility, service quality, satisfaction, motivation and the factor of receiving tips. The analysis showed correlation between methods used to increase the value of tips and better service quality, increased financial and numerical flexibility, motivation, satisfaction upon receipt of tips and the method used to increase the value of tips. In order to decrease labour costs we propose that the management take control of tipping and integrates tips into the reward system. Also, the employees should be made aware about how tipping improves service and increases their income.
Ključne besede: motivation, tipping, flexibility
Objavljeno v DKUM: 06.07.2017; Ogledov: 704; Prenosov: 138
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Organizational flexibility, employee security and organizational efficiency : a case study of Slovenian public and private sector organizationsTatjana Kozjek
, Marko Ferjan
, 2015, izvirni znanstveni članek
Opis: Background: Literature defines different types of flexibility and security with regard to work. Regardless of which type of flexibility or security is discussed, the consequences for individuals, organizations or employers and society are significant.
Purpose: The purpose of the research was to compare and analyse the correlation between the different types of flexibility and security in work and organizational efficiency.
Methodology: Data was gathered using the Computer-Assisted Web Interview (CAWI) method. A link to an online questionnaire was e-mailed to randomly selected organisations across all economic sectors in Slovenia that had a published e-mail address, either in business directories or on a company website. We asked them to forward our e-mail to their employees. The correlation between different variables was used for data analysis.
Results: The results of our research show that there is a low positive level of correlation between different types of flexibility and security in the context of work and also between different types of flexibility in work and organizational efficiency. The correlation between different types of security in work and organizational efficiency is positive and medium strong.
Conclusion: It is recommended that the legislators be aware of the importance of their correlation with organizational efficiency when preparing legislative amendments regarding introduction of the flexibility and security in the field of work.
Ključne besede: flexibility, flexible employment contratcs, employee income security, Slovenia
Objavljeno v DKUM: 04.04.2017; Ogledov: 969; Prenosov: 140
Celotno besedilo (1,04 MB)
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SOLVING THE PROBLEM OF UNEMPLOYMENTEva Lorenčič
, 2013, diplomsko delo
Opis: Unemployment negatively affects the government budget and inflicts costs on the unemployed individuals as well as on the society as a whole in many ways. The direct costs of unemployment for the state budget arise due to the benefits paid out to the unemployed, and due to foregone direct and indirect taxes. On the level of an individual, nonmonetary costs are a multiple of the monetary ones, which indicates that employment plays a central role in a person’s well-being. Unemployment has a spill-over effect on the society as a whole and affects not only the unemployed, but also the employed population, particularly in the areas experiencing high unemployment rates.
We take the case study of Germany, the country often used as a quintessence of how to overcome the problem of massive unemployment. Before the four Hartz reforms, which were implemented in years 2003, 2004 and 2005, Germany was characterized as the »sick man of Europe« owing to its exploding levels of unemployment, dysfunctional labor market, unsustainable social budget, and rising public debt. As the reforms were put into force, the situation in the German labor market underwent a 360° turnaround and became portrayed as the »German economic miracle«. The true effects of the reforms fully transpired in the economic and financial crisis of 2008/2009, when most countries experienced escalating unemployment rates, while Germany kept them at bay. Studies show that flexible working-time arrangements and short-time work have played a major role in inhibiting lay-offs in German companies during the recent crisis, and hence in preventing a spike in unemployment rates, which we use as one of the points that validate our Model of employment. The government subsidies made it possible for companies to reduce the working hours of their employees instead of laying them off. An important feature of the German labor market is a comparatively high percentage of part-time workers (around 25% in years 2006–2011), which also explains the low unemployment rates Germany has been recording since the reforms were introduced. The reforms cut the amount and duration of unemployment benefits, which gave the unemployed more incentives to find a job. A negative aspect of the reform may be an increased divide between the core work force and the marginal workers, which intensifies social differences and is currently on the agenda of German politics. Also some researches stress the importance of social cohesion and that the risks and opportunities in the labor market should be more evenly distributed. In the accompanying explanations to the Model of employment, some of the successful measures of Germany’s Hartz reforms may be spotted, while at the same time we avoid the »mistakes« of these reforms, thus making sure that social differences among people would narrow down upon the real-life implementation of the Model.
When the number of job vacancies sharply exceeds the number of unemployed, and when there are poor prospects of new job openings in the near future, the only viable solution to the problem of unemployment is to reduce the working hours of the existing employees. The Model of employment that we develop represents a possible solution to the problem of unemployment and thus addresses the need to reduce the costs of unemployment to the unemployed individual, to the state budget, and to the society as a whole. The crux of the Model is a re-distribution of the total number of workplaces and total annual working hours among the »new actively employed population«, which comprises all persons having the potential to become or stay employed or self-employed in a given year. The model allows for a flexible arrangement of working hours – from four and up to eight hours per employee per day. Our solution will release the working hours, make them available to the currently unemployed, and hence ensure a more equitable distribution of income and work load amongst the population. In addition, as the workers will be less tired and stressed-out, their productivity will in
Ključne besede: unemployment, labor force, labor market, part-time employment, full-time employment, labor market flexibility, costs of unemployment, Hartz reforms
Objavljeno v DKUM: 30.08.2013; Ogledov: 2309; Prenosov: 166
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Fluctuating excitability : a mechanism for self-sustained information flow in excitable arraysMatjaž Perc
, 2007, izvirni znanstveni članek
Opis: We show that the fluctuating excitability of FitzHugh-Nagumo neurons, constituting a diffusively coupled excitable array, can induce phase slips that lead to a symmetry break yielding a preferred spreading direction of excitatory events, thus enabling persistent self-sustained and self-organized information flow in a periodic array long after a localized stimulus perturbation has sized. Possible oscillation frequencies of the information-carrying signal are expressed analytically, and necessary conditions for the phenomenon are derived. Our results suggest that cellular diversity in neural tissue is crucial for maintaining self-sustained and organized activity in the brain even in the absence of immediate stimuli, thus facilitating continuous evolution of its mechanisms for information retrieval and storage.
Ključne besede: physics, complex systems, dynamical systems, flexibility, chaos, chaotic systems, oscillations, perturbation
Objavljeno v DKUM: 07.06.2012; Ogledov: 2013; Prenosov: 94
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Global nature, global cultureSarah Franklin
, Celia Lury
, Jackie Stacey
, 2000, pregledno delo
Ključne besede: life environment, models, life success, time, genetics, women, women question, theory, culture, nature, power, flexibility, consumption, human, health, efficiency, paradoxes, globalisation
Objavljeno v DKUM: 01.06.2012; Ogledov: 1367; Prenosov: 44
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Renaissance management : the rebirth of energy and innovation in people and organizationsStephen Carter
, 1999, priročnik
Ključne besede: management, renaissance, reengineering, changes, individualism, society, human potential, human resource management, work, employment, creativity, motivation, working power, energetic system, organizational development, working organization, flexibility, team work, manager, partnership
Objavljeno v DKUM: 01.06.2012; Ogledov: 1872; Prenosov: 65
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