Numerical examination of nonlinear oscillators

The numerical examination of nonlinear oscillators is presented in this paper. First some methods of nonlinear system modeling are described then the numerical creation of phaseplane, bifurcation diagrams and Poincaré sections are expounded in detail. The next part of the paper is the numerical examination of nonlinear oscillators, like the Duffing-Holmes oscillator and a mechatronic semi-active suspension system. The paper concludes with further development tasks

Parameter Identification of a Fire Truck Suspension for Vibration Analysis

In case of field measurement it is essential to determine the measurement conditions. With accurate parameter identification credible measurement and simulation results can be achieved. In this paper the parameter identification of a CSD-755-10 heavy-duty fire truck suspension for vibration analysis is presented, which is an important base-point for further research

Stair Climbing Aid Devices as Parts of Sustainable Healthcare

An important aspect of a sustainable society is the care of elderly people. For a sustainable society, it is necessary to develop cost-effective, culture-appropriate, and sustainable eldercare services, which should guarantee both safety and quality. It is also important to prolong the time in which elderly people can live independently to contribute to sustainable healthcare. For elderly people, a daily activity, climbing stairs, might be difficult. This paper presents an overview of stair-climbing aid devices. The paper introduces the sustainable healthcare of elderly people. Then, different stair-climbing aid devices are explained and analyzed, ranging from passive ones to high-tech stair-climbing exoskeletons. A prototype of a new solution, which is an Intelligent Crutch, is presented. After elaborating on the design criteria, the detailed conceptual design and the working principle of the device are presented. The presented concept fills a gap between expensive and complicated stair climbing aid devices and simple and cheaper solutions. It is cheaper and simpler than the active, complicated stair-climbing devices but performs almost the same function. The device helps elderly and disabled people to climb stairs alone, thus improving the quality of life of the target group. The study concludes with further development tasks in order to help elderly people and contribute to a sustainable society

Numerical Examination of a Forest Area Fire

An important task of sustainability is the protection of Earth's forests and the prevention of forest fires. In this paper, the numerical examination of a typical Hungarian ash forest fire is presented. The connection between sustainability and forest fire simulations is also discussed. For the simulation, a Fire Dynamics Simulator was selected, and a particle-based model was used. The simulation setup, which includes a random location of trees following Poisson distribution, is also explained. Then, the simulation of a 10x10 m area of ash forest is presented. It was found that in case of arson, the fire spreads rapidly among the trees, and there will be a high-intensity fire in which the forest area burns down in 4 min. The mass loss rate, the temperature, and the heat release rate also increased fast (above 50 kg/s, above 2,000 °C and above 800,000 kW). The aerosol concentration reached a high pollutant concentration (1.3x10-6), and the carbon dioxide concentration also increased significantly (above 14,000 ppm). These changes have a direct effect on climate change. Therefore, it is important to examine them in a simulation environment. The simulation was compared to a pine tree forest simulation, and it could be observed that in the case of the pine tree, the values are similar, but phenomena occur faster. With the computer simulation, it is easier to determine the areas affected by the fire, which also helps fire prevention and firefighting. The aim of the research is to contribute to the prevention and more efficient extinguishment of wildfires and the sustainability of the Earth

Examination of effects of indoor fires on building structures and people

The scientific study of the harmful effects of indoor fires on building structures and on the environment is a top issue today. Indoor fires frequently occur all over the world. The goal of our research is to examine the effects of an average room fire on the survival possibility of a trapped person and on the building structure, taking into account features of the Eastern European architecture. First, a computational fluid dynamics (CFD) simulation was performed to examine the change of temperature, oxygen, and carbon monoxide concentration in a selected room in a vacant building used for military training. Based on the results, a 1:1 scale fire experiment was carried out with the parameters used in the simulation. The experiment was repeated once with the same settings. It was observed that without the intervention of firefighters, the temperature in the experiment could have rapidly reached 400 °C, as suggested by the simulation, which could have caused structural damage to the building. Furthermore, after 3 min the carbon monoxide concentration reached 400 ppm in both experiments and the simulation, which is a harmful level to people trapped inside the room. Also, in the experiment there was sufficient oxygen at the ground level with what people can survive 3 min