Combinatorial optimization model for railway engine assignment problem

This paper presents an experimental study for the Hungarian State Railway Company (M\'AV). The engine assignment problem was solved at M\'AV by their experts without using any explicit operations research tool. Furthermore, the operations research model was not known at the company. The goal of our project was to introduce and solve an operations research model for the engine assignment problem on real data sets. For the engine assignment problem we are using a combinatorial optimization model. At this stage of research the single type train that is pulled by a single type engine is modeled and solved for real data. There are two regions in Hungary where the methodology described in this paper can be used and M\'AV started to use it regularly. There is a need to generalize the model for multiple type trains and multiple type engines

Student evaluation of teaching effectiveness: implications for scholars in operations management

Many times, teaching rating by students are the most influential measure of the quality of teaching departments, courses and teachers to assess how curricula changes are perceived by students. This study seeks biases introduced by background variables. If these are relevant, then student evaluations as a valid indicator of teaching effectiveness for the purpose of quality improvement and assurance could be questioned. The research purpose is (i) to appreciate the suitability of business student ratings in assessing teaching performance, and (ii) to explore limitations of current practices considering student evaluation as a primary university tool to assess teaching effectiveness.info:eu-repo/semantics/acceptedVersio

Fragmentation Phase Transition in Atomic Clusters II - Coulomb Explosion of Metal Clusters -

We discuss the role and the treatment of polarization effects in many-body systems of charged conducting clusters and apply this to the statistical fragmentation of Na-clusters. We see a first order microcanonical phase transition in the fragmentation of $Na^{Z+}_{70}$ for Z=0 to 8. We can distinguish two fragmentation phases, namely evaporation of large particles from a large residue and a complete decay into small fragments only. Charging the cluster shifts the transition to lower excitation energies and forces the transition to disappear for charges higher than Z=8. At very high charges the fragmentation phase transition no longer occurs because the cluster Coulomb-explodes into small fragments even at excitation energy $\epsilon^* = 0$.Comment: 19 text pages +18 *.eps figures, my e-mail adress: [email protected] submitted to Z. Phys.

Developing a research agenda for digital accessibility in multinational enterprises

Digital accessibility for disabled people is a hot topic of Corporate Social Responsibility, mandatory under current UN and UE dispositions. This research aims at investigating its company-wide administrative integration by developing a systematic process of enquiry producing a diagnosis tool under the guidance of the Soft Systems Methodology (RQ3). Absorptive capacity provided the theoretical umbrella for structuring the problem-situation (RQ1) by setting its Root Definitions. Thus, the expected scientifically supported diagnosing tool should generate feasible and desirable changes to the problem-situation perceptions (RQ2). Digital Accessibility by Design in Service was coined to define this innovative and relevant approach.info:eu-repo/semantics/acceptedVersio

Digital accessibility in multinational enterprises: A meta study

Ever since the ratification of Directive 2016/2102 (Web Accessibility Directive) and EU Directive 2019/882 (European Accessibility Act), digital accessibility has been gaining in importance for public administration and business within the European Union. Furthermore, the role of companies has changed during the last decades and the concept of corporate social responsibility has become increasingly relevant for multinational enterprises. As one aspect of Corporate Social Responsibility, digital accessibility can bring a lot of advantages, for example by driving innovation or by enhancing a company's brand. Therefore, even companies that do not have to meet legal requirements should act with digital accessibility in mind as one part of their Corporate Social Responsibility Strategy. In the current literature and legal regulations, digital accessibility is mostly described as a technical issue, while organizational, structural aspects, and managerial tasks within the implementation of digital accessibility are ignored. By reviewing current literature, this meta-study shows the relevance of digital accessibility for multinational companies, explains why the implementation of digital accessibility cannot only be considered from a technical point of view and discusses initial approaches to examine the integration of digital accessibility into company-wide processes.info:eu-repo/semantics/publishedVersio

Definition of key drivers for project success regarding the General Data Protection Regulation

In the context of the General Data Protection Regulation (GDPR), organisational governance must consider data privacy concerns and regulations. This will avoid illegal situations, the related fines, damage to organisational reputation or, even, temporary/definitive limitation on processing activities. An innovative conceptual model is proposed to deliver the necessary change that addresses GDPR concerns based on the enablers concept. Moreover, project success is (re)examined to include stakeholders perceptions, in addition to organisational effectiveness, which is defined by the respect for legal requirements and by demonstration of compliance with the Regulation at an acceptable cost, i.e. the typical internal deliverables.info:eu-repo/semantics/acceptedVersio

Quark-Gluon-Plasma Formation at SPS Energies?

By colliding ultrarelativistic ions, one achieves presently energy densities close to the critical value, concerning the formation of a quark-gluon-plasma. This indicates the importance of fluctuations and the necessity to go beyond the investigation of average events. Therefore, we introduce a percolation approach to model the final stage ($\tau > 1$ fm/c) of ion-ion collisions, the initial stage being treated by well-established methods, based on strings and Pomerons. The percolation approach amounts to finding high density domains, and treating them as quark-matter droplets. In this way, we have a {\bf realistic, microscopic, and Monte--Carlo based model which allows for the formation of quark matter.} We find that even at SPS energies large quark-matter droplets are formed -- at a low rate though. In other words: large quark-matter droplets are formed due to geometrical fluctuation, but not in the average event.Comment: 7 Pages, HD-TVP-94-6 (1 uuencoded figure

Density of critical points for a Gaussian random function

Critical points of a scalar quantitiy are either extremal points or saddle points. The character of the critical points is determined by the sign distribution of the eigenvalues of the Hessian matrix. For a two-dimensional homogeneous and isotropic random function topological arguments are sufficient to show that all possible sign combinations are equidistributed or with other words, the density of the saddle points and extrema agree. This argument breaks down in three dimensions. All ratios of the densities of saddle points and extrema larger than one are possible. For a homogeneous Gaussian random field one finds no longer an equidistribution of signs, saddle points are slightly more frequent.Comment: 11 pages 1 figure, changes in list of references, corrected typo

Excess GeV radiation and cosmic ray origin

Recent EGRET observations of the diffuse Galactic gamma-ray emission reveal a spectrum which is incompatible with the assumption that the cosmic ray spectra measured locally hold throughout the Galaxy: the spectrum above 1 GeV, where the emission is supposedly dominated by pi^0-decay, is harder than that derived from the local cosmic ray proton spectrum. We demonstrate that in case of a SNR origin of cosmic ray nucleons part of this gamma-ray excess may be attributed to the dispersion of the spectral indices in these objects. In global averages, as are gamma-ray line-of-sight integrals, this dispersion leads to a positive curvature in the composite spectrum, and hence to modified pi^0-decay gamma-ray spectra.Comment: accepted for publication in Astronomy and Astrophysic