Strengthening method of wheelset tires

The main ways to strengthen and increase the resourse of wheelset bandage as result of which it is determined that the most economical and quick-to-implement method is the use of tribotechnical materials are considered. The main disadvantage in using of tribotechnical materials is the limited temperature range of rolling stock operation is determined. Qualitative selection of anti-wear and heat-resistant additives, as well as binder is perfomed based on the physical properties required for tribotechnical materials and the range of component content in the lubricant is determined. The wear resistance of wheelset bands is increased by 28 % as result of performance tests.

Phase Behavior of a Cell Fluid Model with Modified Morse Potential

The present article gives a theoretical description of a first-order phase transition in the cell fluid model with a modified Morse potential and an additional repulsive interaction. In the framework of the grand canonical ensemble, the equation of state of the system in terms of chemical potential–temperature and terms of density–temperature is calculated for a wide range of the density and temperature. The behavior of the chemical potential as a function of the temperature and density is investigated. The maximum and minimum admissible values of the chemical potential, which approach each other with decreasing the temperature, are exhibited. The existence of a liquid-gas phase transition in a limited temperature range below the critical Tc is established.

Phase Transitions and Local Polarity above TC in a PbZr0.87Ti0.13O3 Single Crystal

Solid solutions of PbZr1−xTixO3 (PZT) are one of the most widely used piezoelectric materials with perovskite structure. Despite the decades of research, the phase diagram of PZT reported in 1971 has not been resolved yet. Recently, it turned out that single crystals of good quality of these solid solutions can be grown. By means of top-seeded solution growth (TSSG) technique, we succeeded to grow a single PbZr0.87Ti0.13O3 crystal. Hence, a partial verification of the diagram could be performed through investigations of the optical, dielectric, pyroelectric and elastic properties of this crystal, in a wide temperature range. The obtained results confirmed that the PbZr0.87Ti0.13O3 crystal undergoes a sequence of phase transitions, such as those observed in ceramics of similar chemical composition. However, additional anomalies of investigated physical properties were observed and discussed. Moreover, the influence of electric field on optical properties has been investigated for the first time and has proven the existence of local polar character of the phase above TC in a limited temperature range.

Static structural and thermal analysis of brake disc with different cut patterns

Power transmission plays an important role in automobiles. Since the concern regarding safety in automobiles has been considered as a top priority, it is very much important to have a complete control over vehicle to make it stop. Brakes are the power interruption devices which absorb the kinetic energy of vehicle and bring it to the rest condition. Once the brakes are actuated, heat is generated due to the friction between pads and rotating disc. This heat generated is responsible for high temperature of the disc. As brakes convert friction into heat, it must be dissipated through it in order to have limited temperature range of the entire system. Under this consideration drums brakes have been replaced by disc brakes as they are more efficient under steady and instantaneous braking conditions. In this paper, models were designed by using CATIA-V5 and then imported to ANSYS 16.2 for static structural and thermal analysis. The designing of discs was carried out considering its application for a two wheeler of 200-250 cc engine capacity. The aim of this paper is to study the heat distribution and the overall deformation of the discs having different cut patterns. Further an extension to this work, an attempt has been made to investigate different aspects like deformation and temperature distribution by varying the alloy materials for discs. This analysis has helped us a lot to understand the behavior of different materials under realistic conditions. The paper is then concluded with the best material and cut patterns in terms of strength, factor of safety and heat dissipation.

Static structural and thermal analysis of brake disc with different cut patterns

Power transmission plays an important role in automobiles. Since the concern regarding safety in automobiles has been considered as a top priority, it is very much important to have a complete control over vehicle to make it stop. Brakes are the power interruption devices which absorb the kinetic energy of vehicle and bring it to the rest condition. Once the brakes are actuated, heat is generated due to the friction between pads and rotating disc. This heat generated is responsible for high temperature of the disc. As brakes convert friction into heat, it must be dissipated through it in order to have limited temperature range of the entire system. Under this consideration drums brakes have been replaced by disc brakes as they are more efficient under steady and instantaneous braking conditions. In this paper, models were designed by using CATIA-V5 and then imported to ANSYS 16.2 for static structural and thermal analysis. The designing of discs was carried out considering its application for a two wheeler of 200-250 cc engine capacity. The aim of this paper is to study the heat distribution and the overall deformation of the discs having different cut patterns. Further an extension to this work, an attempt has been made to investigate different aspects like deformation and temperature distribution by varying the alloy materials for discs. This analysis has helped us a lot to understand the behavior of different materials under realistic conditions. The paper is then concluded with the best material and cut patterns in terms of strength, factor of safety and heat dissipation.

Frost Growth Investigation and Temperature Glide Refrigerants in a Fin-and-Tube Heat Exchanger

Biomethane is produced by removing undesirable components such as water vapor, carbon dioxide and other pollutants in a biogas upgrading process. Frosting the water vapor contained in the biogas is one of the dehydration processes used in a biogas upgrading process. In order to simulate a frost layer on a cold plate, many models have been developed. These models are valid for a limited temperature range. In this study, heat and mass transfer equations were used in a numerical approach to model the frost growth and its densification on the external side of a fin-and-tube heat exchanger. The model used in this study is valid for low temperatures from 0[Formula: see text]C to [Formula: see text]C and lower. The evaporation process of temperature glide refrigerants is also modeled from [Formula: see text]C to [Formula: see text]C. The results show a decreased heat transfer rate during frost mass growth on fins and rows. During its growth, frost layer thermal conductivity is relatively low leading to decrease the heat exchanger performance. On the other hand, frost layer thickness increases the external surface blockage, leading to higher pressure drop on the external side. This model has been validated by comparing numerical and experimental results for the biogas outlet temperature.

Fabrication and characterization of brominated matrimid® 5218 membranes for CO2/CH4 separation: application of response surface methodology (RSM)

In the present study, special effort was focused on increasing permeability of matrimid membranes. For this objective, a bromination reaction was carried out. The reaction of bromine with polymer was investigated using Fourier transform infrared (FTIR) spectroscopy analysis. A combination of pristine and brominated matrimid was used to prepare modified membranes due to the fact that brominated matrimid membranes were too delicate. Employing a gas separation membrane unit, the permeability of pristine and modified membranes for pure gases (CO2 and CH4) was studied. Modified membranes were much more permeable and less selective than pristine membranes. In fact, the increase in permeability of modified membranes can be attributed to the rise in the fractional free volume of modified membranes. Thermal properties of modified and unmodified membranes were also studied by thermal gravimetric and differential scanning calorimetry analysis. As a result, thermal resistance of modified membranes decreased in a limited temperature range. Modified membranes indicated smaller values of tensile strength than pristine membranes which were assessed using tensile strength analysis. The parameters which can affect the pure gases permeation through membranes such as, bromine concentration in modified membranes and operating pressure were considered as variables and the experimental design was carried out.

A Comparison Between the Burn Condition of Deuterium–Tritium and Deuterium–Helium-3 Reaction and Stability Limits

The nuclear reaction of deuterium–tritium (D–T) fusion by the usual magnetic or inertial confinement suffers from a number of difficulties and problems caused by tritium handling, neutron damage to materials and neutron-induced radioactivity, etc. The study of the nuclear synthesis reaction of deuterium–helium-3 (D–3He) at low collision energies (below 1 keV) is of interest for its applications in nuclear physics and astrophysics. Spherical tokamak (ST) reactors have a low aspect ratio and can confine plasma with β≈1. These capabilities of ST reactors are due to the use of the alternative D–3He reaction. In this work, the burn condition of D–3He reaction was calculated by using zero-dimensional particles and power equations, and, with the use of the parameters of the ST reactor, the stability limit of D–3He reaction was calculated and then the results were compared with those of D–T reaction. The obtained results show that the burn conditions of D–3He reaction required a higher temperature and had a much more limited temperature range in comparison to those of D–T reaction.

Determination of the melting enthalpy of β phase of poly(vinylidene fluoride)

Wide Angle X-ray Scattering (WAXS), Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared spectroscopy (FTIR) analyses of phase composition and of thermal properties of PVDF samples, crystallized at temperatures 27 - 155 °C by casting from N,N-dimethyl formamide (DMF) solution, are reported. Samples obtained at 27 °C contain only β crystal phase and with increase of casting temperature content of β phase decreases in favor of α phase. Evaluation of combined: phase content (WAXS) and melting heat (DSC), leads to two fold higher than for 100 % α phase value of 100% β melting enthalpy, ΔHβ0= 219.7 J.g-1, which may be justified by strong polar interactions in β phase TTT conformation. The relation ΔHβ0 > ΔHα0 leads either to the thermodynamic stability of β phase in whole temperature range (if Tmβ0 ≥ Tmα0) or to the limited temperature range of thermodynamic stability of α phase (if Tmβ0 < Tmα0).