A review of numerical approaches on decaying arc plasmas in polyatomic C-F-O molecular gas flow with chemical non-equilibrium considerations

This study reviews two numerical models to simulate arc plasma decay in polyatomic molecular gas flows, focusing on chemically non-equilibrium (CNE) effects. The first model addresses C-F-O gas mixtures formed by CO2 with ablated PTFE vapor, incorporating 24 species and 98 reversible reactions with temperaturedependent rates. It predicts plasma composition and electron density during decay. The second model assumes irreversible C5F10O decomposition in CO2/O2 mixtures, validated by equilibrium analysis. Arc decay under free recovery is analyzed, highlighting the impact of reaction kinetics and gas composition on temperature and species evolution

Study of correlation between voltage variation and surface temperature during anode mode transitions in a model vacuum switch

The correlation between the voltage course and the anode surface temperature was studied by combined optical and electrical measurements. Performed analysis of the temporal evolution of electrical and optical signals reveals that in the case of constricted anode attachment a clear correlation between electrode surface temperature and arc voltage occurs. The results of the study provide new opportunities for qualification of electrode materials for switching applications

Commonly used methods to monitor driver’s drowsiness and fatigue with a focus on the interior camera

Some of the main causes of road accidents nowadays are fatigue, drowsiness and driver inattention. In many cases, these accidents are fatal and can cause significant financial loss. Most of these accidents happen between midnight and 6am. One way to reduce the number of accidents caused by these causes is to use an interior camera. This camera can detect fatigue or drowsiness and alert the driver in time, and in the worst case, take over the car and stop safely at the side of the road. The aim of this article is to provide a comprehensive overview of the methods used to detect driver fatigue, drowsiness and inattention. A further objective is then to develop and process a survey that focuses on public awareness and opinions on the integration of interior cameras in vehicles across Europe

Burnout in agile software development

This article examines the relationship between personality traits measured by the HEXACO model and the prevalence of burnout syndrome as measured by the Maslach Burnout Inventory (MBI). The research was conducted on a sample of nine developers working in the IT sector, who were divided into two groups according to project management methods – the agile Scrum methodology and the traditional waterfall approach. The aim of the study was to determine whether the implementation of the Scrum method can contribute to reducing the risk of burnout and how individual personality traits correlate with selected dimensions of burnout syndrome. The results show that individuals with higher extraversion and conscientiousness show lower levels of emotional exhaustion and depersonalization, while honesty-humility and agreeableness have less influence on burnout syndrome. At the same time, the introduction of the Scrum methodology contributed to better work stress management and work organization in most cases. The results are limited by the small sample size, but they can provide valuable insights for further research as a pilot study

The influence of road marking visibility on lateral vehicle position and driving speed

Road markings are a vital element of horizontal signalling, forming an integral part of traffic signalling. Their role in traffic safety involves providing timely warnings, safe guidance, and necessary information to ensure the safe movement of all road users. Under conditions of reduced visibility, often due to weather (night, fog, rain, etc.), road markings are often the only guide for drivers to determine the direction of the road. Research conducted using a driving simulator demonstrated the influence of road markings on driver behaviour, specifically on lateral vehicle position and driving speed. The results indicated that drivers behave differently depending on the visibility of road markings. A total of 31 participants took part in the study, with data collected on driving speed and lateral vehicle position for three different visibility levels of road markings on a straight road and on a right and left curve

Modeling of LTO approach time-in-mode values in MATLAB using the generalized extreme value distribution

The landing and take-off (LTO) cycle, which is used to calculate emissions of aircraft below 3 000 feet, consists of four operating modes, each of which has a standardized time duration or time-in-mode (TIM). In this paper, we model TIM values of the Approach operating mode for two aircraft types (Boeing 737-800 and Airbus A320) arriving on Runway 24 at Prague Václav Havel Airport using the generalized extreme value (GEV) distribution. Predictions of the TIM values are made using the models, and the performance of each model is evaluated. The results show that for both aircraft types, the predicted TIM values lead to total emissions estimates deviating on average by 1 to 2 percent from estimates made using the real TIM values, showing good model performance. The presented approach is also shown to be beneficial in comparison with using the standard TIM value (240 s), highlighting the feasibility of further research in this area as one of the avenues of improving the LTO cycle methodology

Characterization of the switching arc in hydrogen under different pressure conditions

The characteristics of filling gas and its resulting arcing behavior is a major factor influencing the current-limiting and switching performance of gas-filled direct current (DC) switches. The use of hydrogen (H2) or mixtures containing H2 as dielectric gas has shown increased breaking performance in compact DC switches. However, arcs in such gases, especially in pure H2 show a complex fluctuating dynamics, especially at higher filling pressures and by simultaneous use of magnetic blown-off. This paper conducts an electrical and optical study of the rapid and unstable arc behavior in H2 at pressures of 1 and 6 bar using a model switch with arc runners. The results remark the significant impact of filling pressure on the arc voltage and the coupled current limiting performance. Moreover, the arc dynamics become more unstable and faster, and the arc shape becomes strongly distorted. Compared to atmospheric pressure, the rate of increase in arc voltage and arc length are noticeably higher

Carbonizable calcium silicates by CO2 atmosphere in a pressure chamber

The paper deals with the possibility of different calcium silicate minerals namely wollastonite (CS), belite (C2S), and rankinite (C3S2) on their curing in CO2 atmosphere. It describes the laboratory preparation of these individual minerals from p.a. pure chemical clean materials. For comparison a representative sample of natural mined wollastonite was chosen for carbonation as well. Following this, for setting basic parameters analyses determining the properties of the samples by XRD analysis and Rietveld evaluation, particle size characterization by laser granulometry and milling fineness by the Blaine method. It also addresses the issue of forming samples suitable for carbonation using a hydraulic press and the actual curing and conditions necessary for carbonation of the minerals in pressure chamber. It summarizes the measured results of compressive strengths, weight changes and mineralogical evaluation of the composition of the samples before and after carbonation. In the conclusion, together with a summary of the measured findings, it is pointed out what direction further research in this field should be aimed for

RESEARCH ON FLEXURAL CALCULATION THEORY OF REINFORCED CONCRETE T-BEAM STRENGTHENED BY STEEL WIRE MESH AND POLYURETHANE CEMENT (SWM-PUC) COMPOSITE

In order to solve the problem of poor bonding and easy peeling of reinforced concrete structure strengthened by steel wire mesh and polymer mortar (SWM-PM). In this paper, a steel wire mesh and polyurethane cement (SWM-PUC) composite strengthening technique is presented. The flexural properties of one unreinforced beam, two SWM-PM strengthened beams and four SWM-PUC composite strengthened beams were studied experimentally. The experimental results show that the SWM-PUC composite reinforcement layer can improve the load carrying capacity and rigidity of reinforced concrete beams and limit the unfolding cracks significantly. The SWM-PUC composite strengthened beams have pure bending damage and peeling damage between the strengthening layer and the concrete has not occurred. However, SWM-PM strengthened beams with the same SWM reinforcement ratio occurred with peeling damage between the reinforcement and the concrete. On basis of an experimental study, the theoretical formulas for cracking load, ultimate load, deflection and width of crack of SWM-PUC composite strengthened beams are proposed by the simplified stress-strain constitutive relation of the material and the theoretical formulas are deduced with the code. By contrasting the test results with the theoretical computation results, the accuracy of the experiment results and the reliability of the theoretical formulas were verified

Performance evaluation of modified turbulent models in simulating arc quenching process in circuit breakers

Gas circuit breakers rely on rapid gas expansion and turbulent mixing within a converging–diverging nozzle to effectively cool and extinguish arcs during current interruption. The transientarc interruption process involves coupled physical phenomena, including turbulent flow, electric current, convection and radiation. Selection of a suitable flow model is vital in obtaining simulation results matching the experimental data. In this study, the transient behaviour of the SF6 flow during the current ramp-down phase is investigated. Performance of the standard k-ϵ turbulence model is compared with modified k-ϵ models, in which the turbulence dissipation constant C1ϵ is systematically varied to identify the effect on the cooling process. Simulation results demonstrate that the adjustment of C1ϵ can improve the arc cooling process by enhancing turbulent kinetic energy, resulting in maximum rate-of-rise of recovery voltage (RRRV) estimation values similar to the experimental conditions.