Miloš Šeda - Academia.edu (original) (raw)

Papers by Miloš Šeda

Symmetry, Oct 25, 2023

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

European Society for Fuzzy Logic and Technology Conference, 2003

This paper deals with a problem of multicriteria selection assuming uncertainties including lingu... more This paper deals with a problem of multicriteria selection assuming uncertainties including linguistic modifiers both in given data and in queries referring to these data. An approach based on measuring similarities of required properties to values of corresponding fields in relational database records is presented.

DAAAM International Publishing eBooks, 2006

Critical Path Method (CPM) is a well known tool in project scheduling where time duration of acti... more Critical Path Method (CPM) is a well known tool in project scheduling where time duration of activities and their precedence relationships are defined and resource capacities are not limited. In practice, this is usually not satisfied. In spite of this, the CPM serves as a base for more general methods such as PERT, solving the Resource Constrained Project Scheduling Problem (RCPSP), and Job Shop Scheduling Problem (JSSP) when it is represented by a disjunctive graph. RCPSP and JSSP are NP-hard problems and therefore it is necessary to solve them by heuristic methods. Here, with respect to the high number of iterations, the effectiveness of the CPM calculations plays a substantial role. This contribution proposes a new implementation of the CPM using a lexicographical ordering of edges in network graphs and shows that its time complexity is lower than that of classical approaches. This conclusion is verified using a representative sample of benchmarks.

When designing complex safety systems which consist of large scale logical circuits, the basic re... more When designing complex safety systems which consist of large scale logical circuits, the basic requirement is to minimise the number of elements that will implement the given logical functions. This will increase the reliability, and thus potentially the security of the devices. For logical functions with a number of variables of no more than 4, Karnaugh maps are preferred. However, in practice, we encounter much more complex functions, either directly applying Boolean algebra laws or using the Quine-McCluskey method, which is based on their systematic use. However, because this method does not provide a minimal form of logical function, and as a result, there may be redundant expressions, we will show that the additional phase of minimisation means solving the problem of covering all inputs by the obtained output expressions. For the purpose of clear representation and implementation process of post-processing method, the genetic algorithms and simulated annealing were implemented on OR-Library benchmarks.

The YouTube, as currently the most prominent online video portal, is attracting a lot of attentio... more The YouTube, as currently the most prominent online video portal, is attracting a lot of attention of researchers from different areas. In this specific paper, we are dealing with the measurement of the perceived quality of a streaming video by mobile applications. Summarizing the theoretical approaches for measuring the quality of experience (QoE), we present and thoroughly describe an Android mobile platform that uses the YouTube Android API environment and enables to evaluate the way users perceive the quality of streaming videos. All collected results are stored in an online database. Such data then can be analyzed by correlation analysis. Since the switching over of a video being replayed significantly affects the quality of experience while having a negative impact on smooth replay, several methods are suggested that may remove such undesired effects.

WSEAS TRANSACTIONS ON SYSTEMS

The graph colouring problem is one of the most studied combinatorial optimisation problems, one w... more The graph colouring problem is one of the most studied combinatorial optimisation problems, one with many applications, e.g., in timetabling, resource assignment, team-building problems, network analysis, and cartography. Because of its NP-hardness, the question arises of its solvability for larger instances. Instead of the traditional approaches based on the use of approximate or stochastic heuristic methods, we focus here on the direct use of an integer programming model in the GAMS environment. This environment makes it possible to solve instances much larger than in the past. Neither does it require complex parameter settings or statistical evaluation of the results as in the case of stochastic heuristics because the computational core of software tools, nested in GAMS, is deterministic in nature.

Wseas Transactions on Mathematics, 2005

$Research paper thumbnail of Heuristic identification of fractional-order systems$

Sensors, Aug 19, 2021

ECMS 2010 Proceedings edited by A Bargiela S A Ali D Crowley E J H Kerckhoffs, 2010

IEEE Access

The application of flying base stations (FBS) in wireless communication is becoming a key enabler... more The application of flying base stations (FBS) in wireless communication is becoming a key enabler to improve cellular wireless connectivity. Following this tendency, this research work aims to enhance the spectral efficiency of FBSs using the radio access network (RAN) slicing framework; this optimization considers that FBSs' location was already defined previously. This framework splits the physical radio resources into three RAN slices. These RAN slices schedule resources by optimizing individual slice spectral efficiency by using a deep reinforcement learning approach. The simulation indicates that the proposed framework generally outperforms the spectral efficiency of the network that only considers the heuristic predefined FBS location, although the gains are not always significant in some specific cases. Finally, spectral efficiency is analyzed for each RAN slice resource and evaluated in terms of service-level agreement (SLA) to indicate the performance of the framework.

WSEAS TRANSACTIONS ON COMPUTERS

The Steiner tree problem in graphs involves finding a minimum cost tree which connects a defined ... more The Steiner tree problem in graphs involves finding a minimum cost tree which connects a defined subset of the vertices. This problem generalises the minimum spanning tree problem, in contrast, it is NP-complete and is usually solved for large instances by deterministic or stochastic heuristic methods and approximate algorithms. In this paper, however, we focus on a different approach, based on the formulation of a mixed integer programming model and its modification for solving in the professional optimization tool GAMS, which is now capable of solving even large instances of problems of exponential complexity.

Algorithms

The assignment problem is a problem that takes many forms in optimization and graph theory, and b... more The assignment problem is a problem that takes many forms in optimization and graph theory, and by changing some of the constraints or interpreting them differently and adding other constraints, it can be converted to routing, distribution, and scheduling problems. Showing such correlations is one of the aims of this paper. For some of the derived problems having exponential time complexity, the question arises of their solvability for larger instances. Instead of the traditional approach based on the use of approximate or stochastic heuristic methods, we focus here on the direct use of mixed integer programming models in the GAMS environment, which is now capable of solving instances much larger than in the past and does not require complex parameter settings or statistical evaluation of the results as in the case of stochastic heuristics because the computational core of software tools, nested in GAMS, is deterministic in nature. The source codes presented may be an aid because th...

Proceedings of the 2014 15th International Carpathian Control Conference (ICCC), 2014

In this paper, we deal with distribution problems and discuss their restrictions, extensions and ... more In this paper, we deal with distribution problems and discuss their restrictions, extensions and modifications including a possible application in agriculture. The Hitchcock transportation problem can be transformed to other problems using special constraints, and we show even to crop problems from the agriculture application area, but in real situations we must deal with uncertain data because the data can only be estimated. We propose an approach which is inspired by PERT known from project management area.

2011 Eighth International Conference on Fuzzy Systems and Knowledge Discovery (FSKD), 2011

International journal of business and economics, Jan 3, 2009

This paper summarizes and compares approaches to solving the knapsack problem and its known appli... more This paper summarizes and compares approaches to solving the knapsack problem and its known application in capital budgeting. The first approach uses deterministic methods and can be applied to small-size tasks with a single constraint. We can also apply commercial software systems such as the GAMS modelling system. However, because of NP-completeness of the problem, more complex problem instances must be solved by means of heuristic techniques to achieve an approximation of the exact solution in a reasonable amount of time. We show the problem representation and parameter settings for a genetic algorithm framework.

2019 11th International Congress on Ultra Modern Telecommunications and Control Systems and Workshops (ICUMT), 2019

In this paper, several approaches to job shop scheduling problem are presented. A mixed integer p... more In this paper, several approaches to job shop scheduling problem are presented. A mixed integer programming model is derived and, based on this result, it is implemented in the GAMS optimisation software tool. Since the problem is NP-hard, this approach may not be used for large instances, its reasonable bounds are indicated using benchmarks from OR-Library. Here, strategies based on operations and disjunctive graph representations are applied and their time complexities are derived. These representations are also used to heuristically generate feasible solutions from their searching space. Finally, a modification is described of the problem using uncertain processing times of jobs based on fuzzy numbers. Methods for comparing fuzzy numbers are then discussed.

Applied Sciences, 2020

The need to optimize the deployment and maintenance costs for service delivery in wireless networ... more The need to optimize the deployment and maintenance costs for service delivery in wireless networks is an essential task for each service provider. The goal of this paper was to optimize the number of service centres (gNodeB) to cover selected customer locations based on the given requirements. This optimization need is especially emerging in emerging 5G and beyond cellular systems that are characterized by a large number of simultaneously connected devices, which is typically difficult to handle by the existing wireless systems. Currently, the network infrastructure planning tools used in the industry include Atoll Radio Planning Tool, RadioPlanner and others. These tools do not provide an automatic selection of a deployment position for specific gNodeB nodes in a given area with defined requirements. To design a network with those tools, a great deal of manual tasks that could be reduced by more sophisticated solutions are required. For that reason, our goal here and our main cont...

IEEE Access, 2019

In this paper, we focus on the problem of minimising a network of state facilities that provide e... more In this paper, we focus on the problem of minimising a network of state facilities that provide essential public services (schools, offices, and hospitals). The goal is to reduce the size of the network in order to minimise the costs associated with it. However, it is essential that every customer should be able to access an appropriate service centre within a reachable distance. This problem can arise in various scenarios such as a government cutting back on public service spending in remote areas or as a reaction to changing demographics (population increase/decrease). In general, this task is NP-hard which makes the problem particularly hard to scale. Therefore, for larger problems, heuristic methods must be employed to find an approximation of the optimum. To solve this problem with satisfactory results, we have presented an enhanced version of the Genetic Algorithm (GA) based on war elimination and migration operations. This modification overcomes the well-known shortcoming of GAs when the population becomes gradually more and more similar, this results in a diversity decrease which in turn leads to a sub-optimal local minimum. We test the performance of the novel algorithm against the standard heuristic benchmarks on the widely accepted Beasley OR-library dataset for optimisation problems. Finally, we provide a case study based on real-data where a municipality tries to minimise the number of schools in a region while satisfying accessibility and other region-specific constraints.

2018 10th International Congress on Ultra Modern Telecommunications and Control Systems and Workshops (ICUMT), 2018

With the increasing popularity of Software as a Service (SaaS) clouds, software architects face n... more With the increasing popularity of Software as a Service (SaaS) clouds, software architects face new challenges in software architecture design, e.g. efficiently integrating those chosen web services into clouds. In this respect, early quality evaluation of the designed SaaS cloud application is crucial to mitigate the risk of later architectural changes due to a violation of quality requirements (such as response time, network throughput and scalability). Architects need to navigate in a rich set of offered services, a variability of the SaaS cloud environments, which makes it difficult to predict the general approach without time-consuming implementation of application prototypes (using GraphQL, Representational State Transfer (REST), Simple Object Access Protocol (SOAP), and Application Programming Interfaces (APIs) approaches). In this paper, we present an abstract application model designed to select the details with a high level of scalability and efficient interactions between service components. This model is reusable and provides new way of thinking about cloud architecture.