Periodica Polytechnica (Budapest University of Technology and Economics)
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Synthesis Processes of Carbonaceous Material/Conducting Polymer Nanocomposites in Relation to Grafting and Electrochemical Properties for Supercapacitor Application: A Review
Get PDFSupercapacitors are the energy storage devices that have gained increased attention due to high charge storage capacity, fast charge-discharge rate, high specific power and excellent cycle stability. Recently, research on supercapacitors is focused on the development of new electrode materials prepared by surface engineering to obtain superior electrochemical performance. Carbonaceous materials (CM) such as graphene, graphene oxide (GO), reduced graphene oxide (rGO) and carbon nanotubes (CNTs) etc. and conducting polymer (CP) based composite materials have gained increased attention for their use in supercapacitors. The nanocomposites obtained by merely mixing these two components pose some serious drawbacks such as low conductivity or poor film forming ability. The conjugation of CPs to CMs through covalent bonds is able to address these drawbacks. This review mainly provide collective information about various synthetic strategies to obtain CP grafted CMs for supercapacitor application. Herein, we provide information on different CP-CM conjugation reactions for obtaining the composites and their effects on electrochemical performances. The analysis revealed the importance of CP-CM grafting is important for tuning the electrochemical properties of the materials
Comparative Study of Electrospinning Parameters for Production of Polylactic Acid and Polycaprolactone Nanofibers Based on Design of Experiment
Get PDFIn terms of applications, the diameter of nanofibers is one of their most important characteristics. This size is influenced by various process parameters, such as: the concentration, the distance between the needle and the collector, volume flow, etc. In this study, we compared the average diameter of nanofibers made from two different polymers, polycaprolactone and polylactic acid.We investigated the impact of various parameters on the production of nanofibers from polycaprolactone and polylactic acid using the electrospinning technique. We employed a factorial experiment design model to characterize this versatile and efficient fibre fabrication method. By considering the effects of voltage, concentration, distance between the pin and the collector, and flow rate, we established a mathematical model to describe the process. The diameters and morphologies of the resulting fibers were analyzed and compared to each other using SEM analysis. Our findings revealed that, among the studied parameters, concentration had the most significant impact on the diameter of the polymer fibers
Transformative Nanosized Organic Coatings with Euphorbia Condylocarpa/Poplar Tree Bark/Zircon Silicate Hybrid System for Enhanced Industrial Resilience
Get PDFThis study focused on enhancing the properties of interior coatings by incorporating natural additives to minimize potential health impacts associated with traditional additives. Organic additives such as Euphorbia condylocarpa, poplar tree bark, and zircon silicate were employed by utilizing Design Expert for optimization. The optimized formulation demonstrated impressive attributes including the prevention of bacterial and mold growth, high corrosion resistance, effective coverage and adhesion, and resistance to dirt retention. The recommended optimum formulation, Euphorbia condylocarpa (1%), poplar tree bark (1%), and zircon silicate (1%) by using the 2FI model, exhibited an R2 value of 0.9838, indicating a remarkable predictability of the variability in the experimental data. This result emphasized the effectiveness of the proposed model in optimizing the properties of nanosized organic coatings for various industrial applications. Thermogravimetric and differential thermal analysis (TG-DTA) revealed that the additives contributed to the development of flame-retardant properties as the temperature increased and morphology of coating was obtained with optical microscope and scanning electron microscope (SEM). Specifically, Euphorbia condylocarpa exhibited antibacterial, flame-retardant, and hydrophobic properties. The study concluded that the incorporation of euphorbia plant, poplar tree bark, and zircon silicate substances positively impacted the performance of coatings offering a more health-conscious and technologically advanced alternative
The Combined Effect of Glass and Plastic Waste on Concrete Properties: Experimental Study
Get PDFIndustrial waste, including glass and plastic, has become widespread in recent years, harming the nature and environment in which we live. Recycling this waste in concrete appears to be one of the best solutions because of its economic and environmental benefits. In this study, the performance of concrete containing plastic waste in the form of fibers and glass waste as a partial replacement for cement was investigated. The effects of both wastes on workability and air content were studied for fresh concrete mixes, as well as their impact on the chloride penetration and carbonation resistance of hardened concrete. The effect of elevated temperature on the compressive strength, weight loss, and ultrasonic pulse velocity of the different mixes was also tested. The results showed that the combination of two wastes in the same mixture contributed to an improvement in the resistance to chloride penetration by 20.5% in the long term. The addition of glass powder to concrete increases the depth of carbonation, whereas the inclusion of plastic fibers reduces the depth of carbonation
LID Approach to Railway Track Drainage: Determination of Heavy Metal Content in the Embankment of Railway
Get PDFAlong with the increase in global pollution, every part of the urban system, including facilities for the transport of people and goods, is becoming increasingly interesting for the study. The first serious research into the impact of railway traffic on the environment appeared after the year 2000. So far, there have been few studies, the main shortcoming of which is a lack of understanding about pollutant migration. With this in mind, in this paper, an investigation and control of the railway track with regard to the presence, content and migration paths of heavy metals was provided. For the research purposes, X-ray fluorescence spectrometry and optical emission spectrometry with induced coupled plasma were used. It was found that the maximum allowable values were exceeded for cadmium, cobalt, copper, zinc, nickel, vanadium, barium, chromium and iron. In the course of determining the amount of these elements in the railway track, there was also evidence of significant metal infiltration into the lower layers. This indicated the ability of heavy metals to migrate, even through mechanically compacted soil. Detailed knowledge of these issues is of huge importance, which enables the selection of adequate techniques to prevent the migration of heavy metals into the lower layers of the ground and the surrounding soil, among which the elements of Low Impact Development technology stand out in recent years, which could find a very wide and effective application in railway engineering
Formation Mechanism of Rail Corrugation for Modern Tram Lines
Get PDFIn order to explain the phenomenon of corrugation on measured line sections of the modern tram, a numerical model of modern tram-track coupling has been established by utilizing the multi-body dynamics method, and the formation mechanism of corrugation has been studied from the perspective of wheel-rail contact creep. The results show that the smaller the curve radius is, the greater the probability of corrugation occurs. The corrugation wavelength range is 40 mm~50 mm, the wave depth range is 0.05 mm~0.1 mm, and the wave depth is relatively small compared with the corrugation wave depth of metro lines, which is in line with the characteristics of the light-load operation of the tram. The formation mechanism of corrugation on modern tram sharp curves can be described as wheel-rail contact creep saturation leads to the generation of corrugation, and the source of creep is related to the guiding mechanism of the longitudinally coupled independent wheelset bogie. The formation of corrugation on the straight line of the modern tram is related to the difference in wheel diameters between the front and rear wheelsets on the same side, which can lead to different longitudinal velocities, thus generating longitudinal creep forces and inducing rail corrugation
Implementation of New Predictive Control Based Volterra Model for Fast Dynamic Systems Using Microcontrollers: Real Time Application
Get PDFThis paper presents a new contribution in the implementation of Volterra model predictive control for fast dynamics systems. The control approaches considered results on a switch paradigm that combine an online part based on suboptimal solution and an offline part referred to an offline neural network controller. The proposed approach has an advantage in comparison with nonlinear optimization-based control schemes. A real time application on STM32 to control a boost converter is studied and the results show very remarkable performances in time computing
Photovoltaic Microinverter Based on Buck-Boost Converter and Discharge Circuit
Get PDFThis paper presents a novel topology for photovoltaic microinverters that uses a buck-boost converter coupled with a discharge circuit. The system enables efficient conversion of electrical energy from the solar panel without requiring voltage filters or step-up transformers. For its control, an exponential action control strategy is used, as it allows effective tracking of the reference voltage. The stability of the overall control and inverter system is demonstrated and detailed using the Lyapunov method. The sizing of the components used is also detailed. The performance of this topology is evaluated under various load conditions, revealing low harmonic distortion (THD) in both current and voltage, with the best THD of 1% being obtained at a power factor of 0.8. This makes it a promising solution for photovoltaic energy conversion
Improved Power Control Based Variable Speed Wind-Turbine DFIG under Hard Work Conditions: Application of Sliding Mode Theory
Get PDFThis paper introduces an efficient and simple power control for the Wind Energy Conversion System (WECS) based on the Doubly-Fed Induction Generator (DFIG). Due to the limitation performance of the conventional PI controller against DFIG parameters change and wind speed variation; the sliding mode theory is applied in order to overcome these drawbacks. To improve the performances of a WECS, robust and nonlinear control techniques, namely; Conventional Sliding Mode Control (C-SMC) and Third Order Sliding Mode Control (3O-SMC), were implemented to independently control the stator active and reactive powers. However, both techniques exhibited a chattering phenomenon, an undesirable phenomenon caused by discontinuous signals. To overcome this drawback and further enhance previous control techniques, an advanced Variable Gain Super Twisting Algorithm (VGSTA) is proposed and compared to SMC and 3O-SMC. Furthermore, to validate the effectiveness of the proposed VGSTA strategy in comparison to two previous control methods, the WECS was simulated and validates using the MATLAB/Simulink environment. The simulation results clearly demonstrated the superiority of the proposed VGSTA strategy over the previous SMC and 3O-SMC techniques. This was obvious in terms of both fast convergence velocity and reduce chattering phenomenon