In this paper we observed the global dynamics and the occurrence of a certain bifurcation for the corresponding values of a certain rational difference equation of the second order with analyzed quadratic terms. The analysis of the local stability of the unique equilibrium point, as well as the unique periodic solution of period two, was performed in detail. The constraint of the equations on both sides for the corresponding values of the parameters is proved and on this basis the global stability is analyzed. The existence of Neimark-Sacker bifurcation with respect to the arrangement of equilibrium points has been proven. Thus, the basins of attraction have been determined in full for all the positive values of the parameters and all the positive initial conditions.

In this paper we will look at the one system of ODE and analyze it. We aim to determine the points of equilibrium; examine their character and establish the existence of a bifurcation for the corresponding parameter value. A detailed analysis of local stability was performed for all values of the given parameter. For a certain value of the parameter, the existence of supercritical Hopf bifurcation of the observed system of differential equations has been proved. Also, the existence of a limit cycle that is always stable has been proved.

The main objective of this research was to propose a light and practical design solution for electric bike front drive with bottom bracket electric motor. The initial design needs to be redesigned so it can enable simultaneous use of the electric drive and pedal drive, with integration of the front gear shifter. After gathering the basic information linked to the problem and inspecting the initial design solution, the assets and flaws have been identified. The CAD models of the considered possible solutions were developed into FEM models which were used for structural analysis in CAD/CAE software system CATIA. On the basis of the FEM analysis and additional criteria, the optimal solution was chosen, and structural optimization, based on FEM model, was performed. A prototype was manufactured and a mounting process in a place of the initial design was performed. Afterwards, electric bike with mounted prototype was tested under real conditions.

Abstract. In this paper we evaluate characteristics of three optical particulate matter sensors/sizers (OPS): high-end spectrometer 11-D (Grimm, Germany), low-cost sensor OPC-N2 (Alphasense, United Kingdom) and in-house developed MAQS (Mobile Air Quality System), which is based on another low-cost sensor – PMS5003 (Plantower, China), under realistic conditions of strong and mild urban pollution. Results were compared against a reference gravimetric system, based on a Gemini (Dadolab, Italy), 2.3 m3 h−1 air sampler, with two channels (simultaneously measuring PM2.5 and PM10 concentrations). The measurements were performed in Sarajevo, the capital of Bosnia-Herzegovina, from December 2019 until May 2020. This interval is divided into period 1 – strong pollution – and period 2 – mild pollution. The city of Sarajevo is one of the most polluted cities in Europe in terms of particulate matter: the average concentration of PM2.5 during the period 1 was 83 µg m−3, with daily average values exceeding 500 µg m−3. During period 2, the average concentration of PM2.5 was 20 µg m−3. These conditions represent a good opportunity to test optical devices against the reference instrument in a wide range of ambient particulate matter (PM) concentrations. The effect of an in-house developed diffusion dryer for 11-D is discussed as well. In order to analyse the mass distribution of particles, a scanning mobility particle sizer (SMPS), which together with the 11-D spectrometer gives the full spectrum from nanoparticles of diameter 10 nm to coarse particles of diameter 35 µm, was used. All tested devices showed excellent correlation with the reference instrument in period 1, with R2 values between 0.90 and 0.99 for daily average PM concentrations. However, in period 2, where the range of concentrations was much narrower, R2 values decreased significantly, to values from 0.28 to 0.92. We have also included results of a 13.5-month long-term comparison of our MAQS sensor with a nearby beta attenuation monitor (BAM) 1020 (Met One Instruments, USA) operated by the United States Environmental Protection Agency (US EPA), which showed similar correlation and no observable change in performance over time.

An advanced system for determination of face mask efficiency is developed and presented in this paper It is based on a high-end scanning mobility particle sizer (SMPS), which was able to detect nanoparticles from the diameter of 10 nm up to 1000 nm in 129 equidistant channels Two fitting installations for face masks were used: a mannequin doll head, to simulate realistic use of face mask and a tight-fit system which prevents the air leak The SMPS-based system was able to determine mask efficiency for different particle sizes © 2020 Danube Adria Association for Automation and Manufacturing, DAAAM All rights reserved