Eugeniusz Kurgan and Paweł Schmidt
Distribution of the electric potential and current density in the electrode of the proton exchange membrane fuel cell.
Abstract
Purpose
Distribution of the electric potential and current density in the electrode of the proton exchange membrane fuel cell.
Design/methodology/approach
Multicomponent model based on Maxwell‐Stefan equations is used to formulate generalized Fick's law. Next, mass conservation laws for gas components and equation of continuity for current density vector are formulated.
Findings
The problem is expressed by three non‐linear partial differential equations in total molar contraction of the gas mixture, oxygen and water vapor concentration describing multicomponent Maxwell‐Stefan mass transport and fourth equation for electric potential distribution. The final system of partial differential equations describing the problem is highly non‐linear and mutually coupled not only directly but also through the non‐linear boundary condition and is solved by finite element method.
Research limitations/implications
There are some convergence problems for some sets of the material parameters. Only one part of the fuel cell was modeled.
Practical implications
This approach allows one to calculate all important parameters required to develop and design the practical systems as well to optimize the performance from the geometrical and material parameters point of view.
Originality/value
The presented approach combines distribution of mass transport using Maxwell‐Stefan model and electric potential described by Laplace equation.
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Michał T. Lewandowski, Paweł Płuszka and Jacek Pozorski
This paper aims to assess the sensitivity of numerical simulation results of turbulent reactive flow to the formulation of inlet boundary conditions. The analysis concerns the…
Abstract
Purpose
This paper aims to assess the sensitivity of numerical simulation results of turbulent reactive flow to the formulation of inlet boundary conditions. The analysis concerns the profiles of the mean velocity the turbulence kinetic energy k and its dissipation rate ϵ. It is intended to provide guidance to the determination of inlet conditions when only global flow data are available. This situation can be met both in simple laboratory experiments and in industrial full-scale applications, when measurements are either incomplete or infeasible, resulting in lack of detailed inlet data.
Design/methodology/approach
Two turbulence–chemistry interaction models were studied: eddy dissipation concept and partially stirred reactor. Three different velocity profiles and related turbulence statistics were applied to present feasible scenarios and their consequences. Simulations with the most appropriate inlet data were accompanied with profiles of turbulent quantities obtained with a proposed method. This method was contrasted to other approaches popular in the literature: the pre-inlet pipe and the separate cold flow simulations of a burner. The methodology was validated on two laboratory-scale jet flames: Delft Jet-in-Hot-Coflow and Sandia CHN B. The simulations were carried out with open source code OpenFOAM.
Findings
The proposed relations for turbulence kinetic energy and its dissipation rate at the inlet are found to provide results comparable to those obtained with the use of experimental data as inlet boundary conditions. Moreover, from a certain location downstream the jet, weakly dependent on the Reynolds number, the influence of inlet conditions on flow statistics was found to be negligible.
Originality/value
This work reveals the consequences of the use of rather crude assumptions made for inlet boundary conditions. Proposed formulas for the profiles for k and epsilon are attractive alternatives to other approaches aiming to determine the inlet boundary conditions for turbulent jet flows.
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Dmytro Osiichuk, Paweł Mielcarz and Julia Kavalenka
Relying on an international panel data set, the purpose of this paper is to quantify the economic impact of labor unionization on corporate financial performance.
Abstract
Purpose
Relying on an international panel data set, the purpose of this paper is to quantify the economic impact of labor unionization on corporate financial performance.
Design/methodology/approach
Static panel regression analysis is performed for a firm-level multinational data set to elucidate the postulated empirical relationships between employee unionization and corporate performance. The transmission mechanisms intermediating the studied effects are discussed and operationalized.
Findings
The empirical evidence demonstrates that firms with a higher level of employee unionization spend more on wages and labor-related expenses. The concomitant downside of higher resource extraction by unions is a lower rate of net employment creation and a higher possibility of redundancy layoffs.
Originality/value
Overall, the authors demonstrate that by creating a credible threat of employee disobedience manifested through strikes and internal wage disputes, labor unions remain an effective mechanism of increasing employees’ bargaining power. Despite the discovered weak negative associative link between the degree of unionization and corporate financial performance, the authors perceive the overall evidence to be inconclusive on this matter.
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The purpose of the research is to identify the degree of intensity of barriers to the activities of social enterprises (SEs) and to examine the significance of such barriers…
Abstract
Purpose
The purpose of the research is to identify the degree of intensity of barriers to the activities of social enterprises (SEs) and to examine the significance of such barriers regarding the financial situation of SE’s in emerging economies.
Design/methodology/approach
The data relates to 200 SEs selected from a national survey of 1,300 Polish non-governmental organizations (NGOs). An analysis of barriers to SEs according to the frequency of their occurrence was conducted. An indicator of the intensity of barriers to the activities of social enterprises and an indicator on these enterprises’ overall financial condition were determined. Spearman rank correlation analysis was used to assess the relationship between the indices.
Findings
The results of the study indicate that in addition to excessive bureaucracy in public administration and the complex formalities related to the use of private and public funds, SEs have difficulties in maintaining good staff and volunteers, whereas people in key positions reference burnout, not only among their own employees but also in themselves. These have a significant impact on the financial situation of SEs.
Originality/value
This study contributes to the field of social entrepreneurship in two ways. One is at the macro level in that it provides suggestions for public authorities in emerging economies interested in maintaining SEs in good financial condition so that they can effectively fulfil their social functions. The second contribution – the micro approach – is recognizing the extent of the impact of barriers on the financial condition of SEs and also determining the intensity of such barriers with regard to the mobilization of resources by managers, especially in the field of human resources.
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Paweł Witczak, Beata Wawrzyniak and Ewa Napieralska‐Juszczak
To develop a fast and accurate method of calculation of permanent magnet machines.
Abstract
Purpose
To develop a fast and accurate method of calculation of permanent magnet machines.
Design/methodology/approach
Presently two ways exist of modeling of synchronous machines – the classic one, when the concept of inductances Ld and Lq is used and the numerical, time‐stepping approach. The first cannot account for precisely the saturation effects, while the second one is highly time consuming. Proposed algorithm replaces inductances by the distributions of flux densities, which were used for their definition, obtained from finite element solutions. Mathematically, the analysis is converted from the space of trigonometric functions to the more general space of periodic functions.
Findings
The compact algorithm of analysis has been found, making it possible to extend its application to other types of machines.
Research limitations/implications
Validation of the proposed method was done only by cross‐checking with integral parameters coming from finite element solution.
Practical implications
A potentially useful idea of representation of an electric machine for control purposes.
Originality/value
The paper presents original concept of the new approach for the representation of electric machines. Parts of that methodology were discussed among specialists during two international conferences and received positive views.
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Joanna Krasodomska, Paweł Zieniuk and Jadwiga Kostrzewska
This paper aims to identify the changes in the share of large public interest entities (PIEs) in European Union (EU) Member States providing Sustainable Development Goal (SDG…
Abstract
Purpose
This paper aims to identify the changes in the share of large public interest entities (PIEs) in European Union (EU) Member States providing Sustainable Development Goal (SDG) reporting prior to (2017) and after (2019) the implementation of Directive 2014/95/EU and the factors that influence their decisions to provide SDG reporting in 2019.
Design/methodology/approach
The authors use the multilevel theory of social change in organizations as the theoretical background. The sample consists of 341 PIEs based in the EU Member States, for which reports published in 2017 and 2019 are available in the global reporting initiative sustainability disclosure database. The authors analyzed the data using the statistical significance test of equal proportions and the logistic regression model.
Findings
The study findings allow to identify a significant positive change in the share of companies providing a reference to SDGs in 2019 compared with 2017. The research confirms that companies’ engagement in United Nations Global Compact and previous experience in sustainability reporting positively influences the decision to report on SDGs in 2019. Contrary to the expectations, industry, size, SDG implementation score, future orientation of government and corporate governance score do not seem to be relevant factors influencing PIEs’ disclosures.
Originality/value
The paper adds to the understanding of the differences in SDG reporting within the EU, which is seen as a frontrunner in implementing the 2030 Agenda and the SDGs.
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Dmytro Osiichuk and Paweł Wnuczak
The authors document a persistent negative link between contemporaneous trade credit provision and subsequent firm-level operating performance.
Abstract
Purpose
The authors document a persistent negative link between contemporaneous trade credit provision and subsequent firm-level operating performance.
Design/methodology/approach
Textual analysis of firms' profile descriptions is used to study the role of market segmentation and product differentiation in intermediating the nexus between trade credit and corporate performance. The paper relies on dynamic panel regression modeling to investigate the postulated empirical relationships. This approach allows to address endogeneity issues and to test a number of different model specifications.
Findings
Despite fueling short-term sales growth, the more generous trade credit terms are found to be associated with lower post hoc margins and declining overall business profitability. The market share is not affected by firms' proclivity to provide trade credit suggesting that the latter may not be effectively used as a long-term growth enhancement strategy. Firms' similarity to their competitors is found to play a salient role in altering the magnitude of the discovered negative relationship.
Originality/value
The authors find that the intensity of intra-industry competition measured by firms' similarity to their competitors magnifies the discovered negative trade credit-performance nexus. Therefore, generous trade credit may play a more important role in solidifying client–supplier relationships on the more segmented markets with a higher degree of product differentiation.