Table of Contents

  • Mixed variational properties for some fourth-order beam problems

    pg(s) 122-125

    In this paper we study eigenvalue problems for fourth-order ordinary differential equations. These boundary problems usually describe the bending vibrations of a homogeneous beam. Our aim here is to present mixed variational forms depending on a wide class of boundary conditions. In particular, we show when the symmetry in variational formulations is available. This property ensures real spectrum of the corresponding problem. The effect of the theoretical results is illustrated by some realistic examples.

  • Modeling of the 3D unsteady multiscale multiphase fluid flow with shocks: Numerical methods and implementation algorithms

    pg(s) 126-132

    Numerical simulation is widely applied in the fluid dynamic research. Unsteady multiphase flow with high Mach and Reynolds numbers has high physical and mathematical fidelity and a special approach of its correct modeling is required. In this paper the appropriate numerical methods and special algorithms of implementation are developed for high-performance numerical modeling using the modern computational systems. The results of validation tasks and problems of practical importance are presented.

  • Application of Laplace transform in finance

    pg(s) 130-133

    Laplace’s transformation is an important chapter of Mathematical Analysis. At present it is widely used in various problems of signal theory, physics, mechanics, electro – techniques and economics. Laplace’s transformation is the simplest and most economical method that leads directly to the required resolution of many of the various technical problems that arise when solving them. In this paper we will become acquainted with the basic concepts of operational mathematics and its application in economy. Not many analytic solutions exist for present discounted value problems but by using Laplace transform we can deduce some of the closed form solutions quite easily. There will be shown the connection between the current discounted value in finance and Laplace transformation.

  • Air space routing and flights planning: A problem statement and discussion of approaches to solution

    pg(s) 139-142

    Air routing has become an important problem of recent years. Wide implementation of idea to use a free routing airspace (FRA) over the Europe and idea of exploiting FRA as a main airspace management resource to reduce air traffic problems revealed a necessity of a new look to a routing problem. Many previous solutions relied on predefined topology of airways and ability to exploit welldeveloped methods known in graph theory. Meanwhile the problem was current due to many factors needed to be involved in the airspace as a 3D-space: air management restrictions and different air spaces regulation rules, weather conditions, danger areas, aircraft’s characteristics, pilots’ preferences, etc. Moreover, the appearance of FRA has made it inappropriate to use previous algorithms. Most of these algorithms required a definite topology with known routing points connected with predefined edges, while the FRA may have only border points to fly into or fly out of the area and no definite edges inside. The task of constructing the route became the same difficult as obvious: any pilot can fly directly through the FRA, but the route should be built and confirmed prior to a take-off. Problem comes even more evident if considered for the unmanned flying vehicles (UFV) and the need for robots or AI systems to solve the routing problem by itselves. As a topping of the complexity of the problem, one may consider the upcoming difficulties of airspace congestion in FRA. Despite the problem is known for areas close to airports, it is still current to plan routes avoiding flights conflicts in the air and to avoid FRA high congestion. There are different researches on some particular problems and some approaches to solve these problems. Nevertheless, there is no complex problem statement yet. This research was focused on need of understanding the full scope of problems for air routing to understand the ability to build an efficient solution for the problem as a whole.

  • Applying queue theory at study of refusals of requests received in universal automotive service

    pg(s) 143-146

    The refusal of requests received in a universal automotive service workshop in the city of Rousse was investigated. The present work analyses the average monthly requests from the workshop customers. The number of the actual repairs was also determined. The work in the service have been seen as a mass service system with a non-stationary mid-month incoming stream with queries. The basic values of the system parameters were calculated under non-stationary conditions and Mat Lab application was created. After the model has been validated, a service conversion option was proposed to reduce the refusals. The proposed approach can serve as a methodology for analysing and optimizing of the activity of other universal automotive service.

  • Evaluation of robustness in ASR for different ‘front-end’ methods

    pg(s) 147-148

    Some feature extraction methods suffer performance degradation in different environments. So it has become a necessity to search for new methods that perform better in different types of conditions. Therefore we can make a comparison of the new found methods to evaluate their performance and to determine which is best in multi-condition tests in order to have e more robust ASR system.

  • Optimal hydro-thermal coordination with a maximum res power utilization strategy constraints model

    pg(s) 149-152

    This paper presents a formal and practical approach onto the short-term evaluation of the impact of the different RES power generation technologies. All these are considered stochastic and basically unreliable in the active power balance but they also seem to be an irreplaceable part of the electric power generation in the future. Here a generalized hydro-thermal coordination optimization model is presented aiming to help a day-ahead power balance impacts analysis and some further risk assessment to the EPS security and resilience.

  • Researching the capabilities of information technologies for edjucation in design, 3D modeling and visualization of the working of complex mechanisms

    pg(s) 156-159

    This report explores modern means for researching automation of design and construction methods of engineering analysis and integrated production systems. The report is fully adapted for the need of knowledge and skills in the future work of engineering specialists in the field of machine-engineering.

  • Complex spatial modelling possibilities of the socio-economic changes of Hungary – potential approaches and methods

    pg(s) 160-162

    The paper overviews the possible methodological and practical approaches which can be used to create a custom-made toolset for the complex spatial modelling and forecasting of the socio-economic processes of Hungary for the 21th century. The author already participated in projects concerning land cover change and demographic modelling and gathered valuable experience in creating isolated models. In his three-year post-doctoral research programme, the author plans to take a more holistic approach with combining the elements of demography, economy and land use to create an integrated model with feedbacks between the consisting parts. The proposed methodology relies heavily on a scenario-based approach, creating a range of different forecasts from the business-as-usual ones to the highly improbable ones to explore the outer edges of future possibilities. Both local and global future assumptions will be considered during the formulation of the scenarios. An additional goal is to make the prepared modelling tool publicly available.

  • Automatic generation of a national diabetes register from outpatient records

    pg(s) 163-166

    In this paper, we present the construction of Bulgarian National Diabetes Register, using pseudonymized outpatient records submitted to the Bulgarian National Health Insurance Fund. The automatic generation facilitates the construction because it does not burden any medical experts with additional paper work. The Register is a healthcare system integrating natural language processing in large scale and analytics functionalities that provide new views to the information concerning Diabetes Mellitus and diabetic patients in Bulgaria. This successful approach encouraged the authors to initiate a research programme in eHealth focused on collection and analysis of patient data, with the intention to assess the feasibility of secondary patient record use in evaluation of healthcare quality.

  • A model of binding of doxorubicin with heparin and enoxaparin

    pg(s) 167-169

    Chemotherapy is one of the most successful methods of fighting with cancer, but like almost any kind of therapy, it has disadvantages such as severe side effects due to the high dose and/or unrestricted distribution within all body compartments. There have been numerous attempts to overcome these difficulties. The first option is to create a new active compound, what has shown to be very costly and, in many cases, ineffective. The other solution is to develop a new way to transport and release of existing drug in the organism using targeted drug delivery systems. Doxorubicin has been selected as a cytostatic substance that are already approved for medical use. The strategy is based on two features; entrapment of the active ingredient within the carrier by associating it with polymer and release it using external trigger guided by an imaging technique. The doxorubicin can be associated with heparin or enoxaparin. In order to implement the heparin/doxorubicin complex into the carrier structure, the thermodynamics of the aggregate formation need to be quantitatively described. The isothermal titration calorimetry has been used to extract the quantitative measures of its formation and stability, necessary for the designing both; pharmacological strategy and production process. To this end, the theoretical model of the binding has been developed and tested on well-defined experimental systems using heparins with different polymer lengths.

  • Modelling the relationship between saturated oxygen and distoms‘ abundance using weigthed pattern trees with algebraic operators

    pg(s) 170-172

    Machine learning has been used in many disciplines to reveal important patterns in data. One of the research disciplines that benefits from using these methods is eco-informatics. This branch of applied computer science to solve environmental problems uses computer algorithms to discover the impact of the environmental stress factors on the organisms’ abundance. Decision tree type of machine learning methods are particularly interesting for the computer scientists as well as ecologists, because they provide very easy interpretable structure without any practical knowledge in mathematics or the inner working of the algorithm. These methods do not rely only on classical sets, but many of them are using fuzzy set theory to overcome some problems like overfitting, robustness to data change and improved prediction accuracy. In this direction, this paper aims to discover the influence of one particular environmental stress factor (Saturated Oxygen) on real measured data containing information about the diatoms’ abundance in Lake Prespa, Macedonia, using weighted pattern tree (WPT) algorithm. WPT is a decision tree method variant that combines fuzzy set theory concepts, like similarity metrics, fuzzy membership functions and aggregation operators, to achieve better prediction accuracy, improve interpretability and increase the resistance to overfitting compared to the classical decision trees. In this study, we use Algebraic operators for aggregation. One WPT model is presented in this paper to relate the saturated oxygen parameter with the diatoms’ abundance and reveal which diatoms can be used to indicate certain water quality class (WQC). The obtained results are verified with the existing knowledge found in literature.