Relation between Kinetic Friction Coefficient and Angular Acceleration during Motion Initiated by Dynamic Impact Force

The paper presents theoretical and experimental analyses of the kinetic friction coefficient of a ball bearing in conditions of rotational motion initiated by dynamic impact force. A method has been developed and a measurement system allows the measurement of a kinetic coefficient of friction through the measurement of the angular acceleration. This paper considers the friction caused by rotational motion initiated by the force impact impulse. After the external force (impact impulse) stops acting, the motion continues, and the loaded bearing (i.e. the zone of the bearing in which the frictional resistance forces act) exhibits a broad spectrum of velocities, from the maximum value at the moment of motion initiation to the zero value when motion stops, where the whole measuring system acts as a rotary encoder. Experimental results indicate a high dependency between angular velocity and friction coefficient, similar to functional dependency. This paper proves that kinetic friction coefficient can be reliably measured using the measurements of angle change and angular velocity. Analysed method has high potential in the diagnostics of energy loss in the tribo-mechanical systems

Computerâ aided detection of breast masses on full field digital mammograms

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134868/1/mp7327.pd

Empirical Analysis of the Influence of Digital Marketing Elements on Service Quality Variables in the Small- and Medium-Sized Enterprises Sector in the Republic of Serbia

Understanding users’ needs, the continuous growth of the quality of a rendered service, and the differentiation of services is imperative in order to attract new users and retain the existing ones. Numerous authors have conducted different empirical research studies to this day, and those studies have mainly dealt with the influence of the quality of services on user satisfaction and loyalty. This paper has made a step forward by including in the research an analysis of the influence of certain elements of digital marketing activities on service quality variables. The research study is aimed at determining how digital marketing elements influence service quality variables in the small- and medium-sized enterprises sector (SMEs) in the Republic of Serbia. This research study should help perceive the interdependence and the degree of the influence between the said elements, which may be helpful to managers of SMEs for preparing the plans, strategies and good practices that increase user satisfaction and loyalty

Evaluation of an algorithm for finding a match of a distorted texture pattern in a large image database

Evaluation of an algorithm for finding a match for a random texture pattern in a large image database is presented. The algorithm was designed assuming that the random pattern may be subject to misregistration relative to its representation in the database and assuming that it may have missing parts. The potential applications involve authentication of legal documents, bank notes, or credit cards, where thin fibers are embedded randomly into the document medium during medium fabrication. The algorithm achieves image matching by a three-step hierarchical procedure, which starts by matching parts of fiber patterns while solving the misregistration problem and ends up by matching complete fiber patterns. Performance of the algorithm is studied both theoretically and experimentally. Theoretical analysis includes the study of the probability that two documents have the same pattern, and the probability of the algorithm establishing a wrong match, as well as the algorithm's performance in terms of processing time. Experiments involving over 250,000 trials using databases of synthetic documents, containing up to 100,000 documents, were used to confirm theoretical predictions. In addition, experiments involving a database containing real images were conducted in order to confirm that the algorithm has potential in real applications

Assessment of Employees Competences Carried out by Different Management Levels

The success of any organization depends on the human resources, their knowledge and skills, and their competencies. Competenceis are developed for the needs of business and the organization in which the individual is working. The aim of the study was to determine how the managers of different levels judge competencies of their employees. The results showed that managers value the most employees eager to learn something new in order to improve knowledge and skills, while the least valued competence is planning and verification of the task before relalization in all of its stages. The results also showed that managers of different levels variously estimate certain competence of their employees

Research of risk taking and deviations from rules at an open pit mine in Serbia

Introduction/background: The paper pointed out the main elements of the human risk factor procedures shows the complexity of human risk factor management. Aim of the paper: The aim of this paper is to analyze the human risk factor in open pit mining, especially on compliance with safety rules and regulations. Materials and methods: The presented survey, in the form of a questionnaire, was conducted in an open pit coal mine involving 476 mineworkers. The goals were to determine factors with the biggest influence on risk and to create a model for predicting the behavior of mining workers. Results and conclusions: The obtained results indicate that leadership plays an important role in worker behavior. A supportive leadership style results in more responsible employee behavior and a lower probability of deviation to rules and procedures. The result also indicates that the safe behavior of workers is strongly influenced by the difficult to control factor of "life satisfaction". It has also been found that riskier work and longer work experience increases the likelihood of breaking the rules. Research limitations/implications: The obtained results are partly influenced by national culture. Practical implications: The obtained results indicate the need for continuous improvement in the risk management process and the rules and procedures by applying worker feedback

Development of a multi-criteria model for sustainable reorganization of a healthcare system in an emergency situation caused by the COVID-19 pandemic

© 2020 by the authors. Healthcare systems worldwide are facing problems in providing health care to patients in a pandemic caused by the SARS-CoV-2 virus (COVID-19). The pandemic causes an extreme disease to spread with fluctuating needs among patients, which significantly affect the capacity and overall performance of healthcare systems. In addition, its impact on the sustainability of the entire economic and social system is enormous and certain sustainable management strategies need to be selected. To meet the challenges of the COVID-19 pandemic and ensure sustainable performance, national healthcare systems must adapt to new circumstances. This paper proposes an original multi-criteria methodology for the sustainable selection of strategic guidelines for the reorganization of a healthcare system under the conditions of the COVID-19 pandemic. The selection of an appropriate strategic guideline is made on the basis of defined criteria and depending on infection capacity and pandemic spread risk. The criteria for the evaluation of strategic guidelines were defined on the basis of a survey in which the medical personnel engaged in the crisis response team during the COVID-19 pandemic in the Republic of Serbia participated. The Level-Based Weight Assessment (LBWA) model and Measuring Attractiveness by a Categorical-Based Evaluation Technique (MACBETH) method were used to determine the weight coefficient criteria, while a novel fuzzy Ranking of Alternatives through Functional Mapping of Criterion Subintervals into a Single Interval (RAFSI) model was used to evaluate the strategic guidelines. The proposed multi-criteria methodology was tested in a case study in the Republic of Serbia. The validity of the proposed methodology is shown through the simulation of changes in input parameters of Bonferroni aggregation functions and through a comparison with other multi-criteria methodologies