Andrej Škraba

• Professor
• University of Maribor

This paper presents the collaborative efforts of researchers and educators from Albania, Croatia, Slovenia, and North Macedonia in updating a tutorial for Open Educational Resources (OER) as part of the Integrating Digital Content and Digitalization of High Schools (iDADOHS) project. Brainstorming sessions generated 46 ideas for enhancing OER tutor...

This paper is a systematic literature review on use of the Deep Reinforcement Learning (DRL) and Graph Neural Networks (GNN) in warehouse. We first explore the use of DRL and GNN for optimization of order picking and batching in warehouse. Because of very little results on use of GNNs in optimization of order picking and batching we extended our se...

Message from the Chairs, The 5th Summer School on Cyber-Physical Systems and Internet of Things (SS-CPS&IoT’2024) is the fifth school in a series, organized in Budva, Montenegrin andMediterranean pearl.We were pleased to continue the tradition of hosting the SS-CPS&IoT’2024 in a hybrid format, accommodating both online and in-person participation.S...

The COVID-19 pandemic has underscored the critical importance of predictive modelling in managing healthcare resources and shaping public health policies. This paper explores the application of advanced Artificial Intelligence (AI) techniques, specifically decoder-only transformer neural networks (DOTNN), in forecasting weekly Intensive Care Unit (...

The aim of this paper is to explore the key factors and interrelationships within a system that examines the impact on how climate change affects wine quality and working practices in vineyards and how winegrowers can adapt to these changes while maintaining their unique wine characteristics. We utilize systems thinking and the system dynamics mode...

A modification of the brainstorming process by the application of artificial intelligence (AI) was proposed. Here, we describe the design of the software system “kresilnik”, which enables hybrid work between a human group and AI. The proposed system integrates the Open AI-GPT-3.5–turbo model with the server side providing the results to clients. Th...

Modification of the brainstorming process by the application of artificial intelligence (AI) is proposed. System design of the software tool “kresilnik” is provided, which enables hybrid work of the human group and AI. The proposed system integrates OpenAI-GPT-3.5-turbo model with the server side providing the results to clients. The proposed archi...

The possibility to apply modern AI tools such as ChatGPT and Ayoa at the design of regional development plan of Gorenjska region is considered. With both systems 496 ideas were generated in the scope of human resources development. Generated ideas were categorized using Latent Dirichlet Allocation, Non-negative Matrix Factorization, human experts a...

Background The COVID-19 epidemic has shown that efficient prediction models are required, and the well-known SI, SIR, and SEIR models are not always capable of capturing the real dynamics. Modified models with novel structures could help identify unknown mechanisms of COVID-19 spread. Objective Our objective is to provide additional insights into...

Digitalna preobrazba se nanaša na uporabo digitalnih tehnologij za poenostavitev poslovanja, povečanje učinkovitosti, inoviranje proizvodov in storitev, prilagajanje potrebam strank, spreminjanje načinov dela in povezovanja znotraj in med organizacijami. Ima širši vpliv, zato je pomembno, da jo obravnavamo celovito (z vidika ekonomije, družbe in ok...

In this paper, we present hardware-software methodology to measure and calculate heart and respiratory rates by using single, low-cost microcontroller chip of limited computation and memory performances, as ATTINY85. Sensors and analog front-end are very simple, directly interfaced to microcontroller pins. Implemented time and frequency domain sign...

The article reviews the literature and development history in the field of group collection of ideas and decisionmaking. Methodology aspects as well as technical realization of tools are considered. Special emphasis is placed on the review of new technologies, which enable new functionalities and approaches. Novel system structure for collecting an...

Approach to modeling a simple Susceptible-Infected (SI) dispersion model of the spread of the epidemics has been addressed. An agent-based model has been developed in JavaScript, which considers the movement of the agents and their contacts. The corresponding model in the form of differential equations has been presented and the calculation of the...

This paper presents the process and impact of the application of a group decision support system (GDSS) in the reform of post-Bologna graduate and postgraduate study programmes in two higher education institutions in Slovenia. Four experiments with four groups including both students and staff were performed. We have used the GDSS tool TeamWorks to...

Purpose This paper aims to analyse the main variables and causal relationships in the system structure of the diversification of non-agricultural activities on agricultural holdings using system dynamics (SD) modelling. The SD model aims to simulate depictions of the behaviour of the real system while testing the effects of alternative decisions ov...

A low cost, simplified hardware and software interface capable of measuring and analyzing photoplethysmogram signal is presented in this paper. Two most important vital signs, oxygen saturation and heart rate are extracted, while the same principle can be extended to other parameters associated to this signal. Overall system consists of specially d...

The paper addresses the development of the system for the parameterization of the Bass Diffusion Model on Covid-19 Data. Continuous model developed by the principle of system dynamics is presented. The parameters of the model are tuned to fit the data with genetic algorithm in Powersim simulation tool. The validation is performed by standard simula...

The paper addresses the problem of efficient organization of the registration process to assure short queues and waiting times at the registration of participants at the conference event. A simulation model of the participants’ registration in an educational event was developed using AnyLogic PLE software. Data was collected from a particular event...

The development of effective organizational systems is one of the most important factors of business success. Radical economic and political changes and the rapid development of the global economic environment trigger public debates in all social structures on the state of entrepreneurial culture, based on generally accepted ethical and legal princ...

Tourism is a type of inter-organisational system with global and local properties. Problems are defined softly and phenomena are uncertain. There are demands for fast and integrated decisions for guest satisfaction as service users and tourism organisations as service providers. There are many different methodologies and methods that master softly...

Background: This paper addresses the problem of products’ terminal call rate (TCR) prediction during the warranty period. TCR refers to the information on the amount of funds to be reserved for product repairs during the warranty period. So far, various methods have been used to address this problem, from discrete event simulation and time series,...

Background: Besides visiting the main tourist attractions in Slovenia, many tourists want to spend their free time in the countryside as well, but the number of farming establishments in Slovenia diminished distinctly in the last years. Objectives: This paper aims to develop a system dynamics model, with the goal to analyse dynamics of the diversif...

In this paper, an approach to the development of medical wearables is proposed. The system integrates sensing modules, Wi-Fi microcontroller and Web browser based user interface. As an example, ECG-PPG monitor is presented. The signals are acquired by AD8232 ECG amplifier module and MAX30102 PPG and SpO2 system on chip. The ESP8266 microcontroller...

In this paper, an approach to the development of medical wearables is proposed. The system integrates sensing modules, Wi-Fi microcontroller and Web browser based user interface. As an example, ECG-PPG monitor is presented. The signals are acquired by AD8232 ECG amplifier module and MAX30102 PPG and SpO2 system on chip. The ESP8266 microcontroller...

Control systems kit for studying the PID principles was developed using affordable microcontroller Arduino UNO and ARM Mini PC Raspberry Pi 3 Model B as well as GK802V5LE. PID algorithm in JavaScript/ECMAScript is provided. The concept of the Cyber-physical System is addressed and the possibility to extend the classical control system paradigm. A d...

Present paper describes the development and implementation of the DC motor simulation model in the framework of Cyber-physical systems and Internet of Things for the educational purposes. In order to provide the testbed for students, the control system and simulation model should be developed in unified environment. This has been achieved by using...

A cyber-physical system for a speech-controlled wheelchair has been proposed. It is based on cloud-harvesting principles, which result in significant improvement in command error rate (CER). The overall methodology and developed cloud-harvesting algorithm have been presented, discussed, and tested. The combination of IBM Watson and Google Cloud Spe...

In today's life, the stress is a leading cause of many illnesses, social and economic problems. There is an inherent need to monitor stress in real time and control it. Many wearables for this purpose are existing on the market, as well as those for physical activity (pedometers) and fitness. However, they are not suitable for research, development...

The aim of this paper is to present two different architectures for evaluating individual or group stress levels. First, the cloud architecture is presented in which a client device is used simply to detect an ECG (electrocardiographic) or PPG (photoplethysmographic) signal and transmit it in raw form to a server, where all the signal processing an...

In the present paper, the cloud based system for monitoring stress in a group of people is presented. It consists of wearable, personized, SPPLC (sensoring-preprocessing-local communication device), WIFI router and CHS/C (code hosting server/cloud) module. The system architecture will be presented as well as several hardware and software details in...

“Simulation Based Decision Support and Business Intelligence” was the title of the last conference session so many of us got used to attending at the Annual Meeting of the International Institute for Advanced Studies (IIAS) and the International Conference on Systems Research, Informatics and Cybernetics in Baden-Baden, Germany. The symposium was o...

Distribution of collisions per particular agent in agent-based market absorption model is considered, where the random initial positions are set and random x-y velocities within range [-0.5, 0.5). Agent class has been defined and object oriented JavaScript code is provided. 135 simulation runs were conducted for 10,000 time steps in order to determ...

The purpose of this study is to describe the principles of the development of parallel system-dynamics and agent-based models of organic farming for the case of Slovenia. The advantage of agent-based modeling is demonstrated by including geospatial information as an agent attribute. The models were compared by the validation, confirming the appropr...

Article describes experiences in the teaching of a modelling and simulation course for students at Faculty of Organizational Sciences. The course consists of time-continuous simulation based on System Dynamics (SD) and discrete event simulation (DES). It is held in the 3rd year of studies, at which point students have taken courses in mathematics,...

The paper presents the transformation of cobweb model by including the anticipation about the supply and demand. Developed transformation leads to oscillatory behaviour. The periodic conditions of the model have been analytically determined by the application of z-transform. Periodic solutions of the system are presented in the form of an inverse F...

Present paper addresses an approach to determine optimal recruitment and transi- tion strategies in strict hierarchical manpower system by the application of simula- tion modeling and optimization methods. The transition model is represented in the form of discrete state space. The target values for each particular rank are deter- mined by the user...

The paper describes the development of the three prototypes which enable monitoring of heart pulse sensor data on the cloud. The prototypes are based on a) Bluetooth module, b) Low Energy Bluetooth module and c) ESP8266 Wi-Fi module. The client side implementation is developed by the application of JavaScript. Node.js was used on the server side wi...

Slovenian primary schools must adhere to a complex curriculum imposed by the Ministry of Education, Science and Sport of the Republic of Slovenia. This complexity makes the scheduling problem challenging. To address this problem, we developed iUrnik, an interactive and automated scheduling system that generates near-optimal schedules using evolutio...

Background and Purpose: The restructuring of human resources in an organization is addressed in this paper, because human resource planning is a crucial process in every organization. Here, a strict hierarchical structure of the organization is of concern here, for which a change in a particular class of the structure influences classes that follow...

This paper describes the development of a prototype speech-controlled cloud-based wheelchair platform. The control of the platform is implemented using a low-cost WebKit Speech API in the cloud. The description of the cloud-based wheelchair control system is provided. In addition to the voice control, a GUI is implemented, which works in a web brow...

Background and Purpose: In a complex strictly hierarchical organizational structure, undesired oscillations may occur, which have not yet been adequately addressed. Therefore, parameter values, which define fluctuations and transitions from one state to another, need to be optimized to prevent oscillations and to keep parameter values between lower...

The actual trends and scenario-based traffic modeling of Ro-Ro automobile terminal in the Port of Bar (Montenegro) are presented. This paper firstly deals with the performance indicators and traffic analysis of Ro-Ro automobile terminal, which faced a fast growth in the past few years. The aim of the paper is related to the traffic and frequency an...

The paper describes the development of prototype wheelchair platform controlled by the gestures. Leap Motion Controller is used to acquire data while changing the hand position. The novel user interface was developed, which shows the hand position to the user and combines the classical button GUI switchboard. The developed system is cloud based and...

This paper describes the problem of human resource management which can appear in many organiza- tions during restructuration periods. The problem is simulated by a dynamic model, similar to a supply chain model with several ranks. The problem of finding the optimal combination of transition coefficients, including the fluctuation coefficients, is...

In this paper a system dynamics model for organic farming development to support government decision making is presented. The system incorporates relevant variables which affect organic farming development. The user seeks answers to strategic questions related to the level of organic farming development achievable in a long term dynamic horizon. Th...

This paper addresses the problem of the hierarchical manpower system control in the restructuring process. The restructuring case study is described where eight topmost ranks are considered. The desired and actual structure of the system is given by the actual numbers of men in a particular rank. The system was modelled in the dicrete state space w...

The aim of this paper is to employ the use of multi-criteria analysis in quantification of the multifunctional agriculture (MFA). For this purpose, two methodological approaches are used and compared: Analytical-Hierarchical Process (AHP) for group decision making and multi-attribute utility theory (MAU T), under the assumption that MFA in Slovenia...

The paper tackles the issue of restructuring strictly hierarchical organizational structure. System that allows the determination of strategies for achieving the desired states is developed using the programming language JavaScript/ECMAScript. It consists of a simulation model based on system dynamics, genetic algorithms, finite state automata and...

This paper describes the development of the prototype speech controlled cloud based wheelchair platform. The control of the platform is implemented using low-cost available speech WebKit in the cloud. Besides the voice control, the GUI is implemented which works in the web browser as well as on the mobile devices providing live video stream. The pl...

Background: The sugar beet is the main field crop used for sugar production in the temperate climatic zone. The abolishment of the quota system will open new investment opportunities in countries that were forced to abandon sugar industry as the result of the reform in 2006. Present paper describes the modeling of sugar beet production and its proc...

The paper addresses an important part of enterprise activity, which is the warranty claims control and prediction. Warranty claims have a significant impact on the financial aspect of the company, because of the funds that need to be reserved for repair of the defected products within the warranty period. The failure process is considered as a comb...

Simulation modelling of traffic in the Kotor cruise port is used for performance evaluation and optimization of the operational policy. During the summer, the traffic intensity of the cruise ships’ arrivals is higher than in other periods of the year. The increased traffic intensity causes congestion at anchorages, which can lead to significant dis...

This paper presents the system dynamics model of organic farming development in order to support decision making. The model seeks answers to strategic questions related to the level of organically utilized area, levels of production and crop selection in a long-term dynamic context. The model will be used for simulation of different policy scenario...

The effectiveness of several operational activities, necessary to ensure security and protection of our territory, heavily relies on effective collection, processing, mining, filtering and visualisation of information regarding events or conditions that can be related to real world locations. As a result, recent years have seen an increasing role b...

We describe a GIS-based real-time system for emergency response and management of air pollution accidents in an urban area. The system architecture emphasises the integration of meteorological, chemical and GIS data, dispersion modeling, decision-making and geo-spatial visualization. The threat zones, unsafe areas and safe traffic routes are obtain...

In this chapter, the authors discuss system dynamics (SD) as a research methodology in Information Systems (IS). The goal is to demonstrate the usefulness of SD methodology in research and its implementation in IS and management Information Systems (MIS). The authors briefly discuss the fundamentals of SD methodology models and causal loop diagrams...

In this paper we describe GEPSUS-W, a wearable system for hazardous gases dispersion simulation in case of manmade accidents. The system architecture, simulation methodology and preliminary results are elaborated. Emphasis is given to real-time embedded systems that allow automatic data entry and on the spot responder interaction with situations. T...

In this chapter, the authors discuss system dynamics (SD) as a research methodology in Information Systems (IS). The goal is to demonstrate the usefulness of SD methodology in research and its implementation in IS and management Information Systems (MIS). The authors briefly discuss the fundamentals of SD methodology models and causal loop diagrams...

In this chapter, the authors discuss system dynamics (SD) as a research methodology in Information Systems (IS). The goal is to demonstrate the usefulness of SD methodology in research and its implementation in IS and management Information Systems (MIS). The authors briefly discuss the fundamentals of SD methodology models and causal loop diagrams...

Purpose This paper aims to describe the development and application of a manpower planning system for the Slovenian armed forces using a system approach, system dynamics (SD) and numerical optimization. Design/methodology/approach The model of the hierarchical manpower system was developed by SD methodology and formulated in discrete time space. T...

This article describes the problem state of organic farming development and procedures for modeling by the means of system dynamics, with emphasis on the organic products market. The modeling principles are described in the following steps: problem state formulation, development of causal loop diagrams, model development, scenario analysis and form...

This paper addresses the impact of feedback information and facilitation on a decision-making process supported by a system dynamics model. We conducted the Solomon Four-Group Experiment under four conditions: (a1) interrupted individual determination of a strategy supported by a simulation model and a facilitator; (a2) interrupted individual deter...

The simulation models are used as for decision support and learning in enterprises and in schools. Tree cases of successful applications demonstrate usefulness of weak anticipative information. Job shop scheduling production with makespan criterion presents a real case customized flexible furniture production optimization. The genetic algorithm for...

The design of strategies for social systems requires the use of qualitative information owing to the fact that quantitative information can be insufficient to solve the problems involved. The information that the specialists and the decision makers obtain is often incomplete and unreliable. Nevertheless, leaders have to make strategic decisions des...

This paper describes experiences in teaching of a Modelling and simulation course at the Faculty of Organizational Sciences. The course consists of continuous simulation based on System Dynamics (SD) and discrete event simulation (DES). When enrolling the course the students have already taken courses of Mathematics, Statistics, Systems Theory, as...

This article addresses the development and application of a simulation model of human resources transitions in the Slovenian armed forces. The system is modeled as an exponential delay chain by means of the Systems Dynamics methodology. The control strategy is determined according to the prescribed final states of a particular rank. In order to ach...

This article describes the problem state of organic farming development and procedures for modeling by the means of system dynamics, with emphasis on the organic products market. The modeling principles are described in the following steps: problem state formulation, development of causal loop diagrams, model development, scenario analysis and form...

Organic agriculture is the highest environmentally valuable agricultural system, and has strategic importance at national level that goes beyond the interests of agricultural sector. In this paper we address development of organic farming simulation model based on a system dynamics methodology (SD). The system incorporates relevant variables, which...

This paper discusses the development of the educational simulator for All Armenian Internet University (HHH University) and Faculty of Organizational Sciences University of Maribor Slovenia. In the developed simulator, lecturers can set information related to educational fields and students can bid and examine the educational fields with lecturers....

The paper describes development of continuous and discrete model of human resources transitions in large organization. The model considers eight different ranks. The calibration of the model was performed where the historical data was used to determine time constants of transitions and fluctuations. Basic simulation runs were performed in order to...

This paper presents a real case study of warehouse replenishment process optimization on a selected sample of representative materials. Optimization is performed with simulation model supported by inventory control algorithms. The adaptive fuzzy inventory control algorithm based on fuzzy stock-outs, highest stock level and total cost is introduced....

The concept of feedback-anticipative control as the extension of classical Wiener paradigm is considered in the context of multi agent systems. The behavior of complex real world agents is based on the consideration of feedback information as well as on the anticipation. A linear model of the agents with a nonlinear interaction rule is proposed as...

This paper analyzes seven years of experience in a concrete production company where reengineering was conducted by employing simulation methodology and AHP methods for decision support. A predictive validation of the simulation model as well as evaluation of the simulation methodology for decision assessment in enterprises was performed by compari...

The research project addresses the influence of feedback information on the decision process supported by the application of system dynamics models. A user-friendly application was developed and used in the experiment with decision groups. The participants were 174 undergraduate management science students. They had the task of determining the opti...