Papers by Keyword: DTG

Abstract: This study aims to determine the key thermal parameters of plastic waste degradation, specifically polyethylene terephthalate (PET), polypropylene (PP), and polystyrene (PS), using differential scanning calorimetry (DSC), differential thermogravimetry (DTG), and thermogravimetric (TG) analysis. The thermal stability of these materials was evaluated by analyzing residual solid and wax quantities, conversion percentages, liquid and gas product yields, and process duration. Experiments were conducted at 550–600°C with a heating rate of 50°C/min. Key thermal parameters investigated include onset decomposition temperature, temperature at 50% conversion, completion temperature, maximum DTG temperature, peak DTG value, melting point, and pyrolysis temperature. The activation energy for mass loss was calculated, ranging from 35 to 68 kcal/mol, with PS exhibiting the highest thermal stability (68 kcal/mol). The degradation conversion efficiency ranged from 85% to 99%. Notably, PET pyrolysis produced significantly more solid residues (0.136–0.150 g/g₀) than PP and PS (0.006–0.088 g/g₀). These findings provide valuable insights into the thermal behavior of plastic waste, supporting advancements in waste management and energy recovery applications.

Abstract: The corrosion product so-called black powder forms inside gas pipelines and negatively affects gas pipelines during the flow of gas therefore it needs continuous follow-up, collecting, and regular maintenance, to understand its physical characteristics and its nature is necessary for field operators to select the appropriate separation technique and to understand the possible roots causing the formation, there are certainly nanoparticles in the form of a large portion due to the effect of heat and moisture. The purpose of present work is to spot the light on black powder produced in gas pipelines by identifying the organic deposit around it, determining the percentage of deposit, determining the kinetic parameter, and thermodynamic parameters by utilizing TGA. Identification of metal power has been achieved by RDX. The black powder was subjected to three identifications first FTIR was to get clear information about the nature of the powder. It showed that the major was organic sulfurs and aromatic hydrocarbons deposited on the outer surface, XRD identified the kinds of iron oxides of iron oxide Fe₂O₃, and hydrated iron oxide FeOOH that formed mainly due to water condensate at dew point and water of periodical upsets, third TGA and DTG to determine the kinetics, and thermodynamics parameters and the percentages of organic hydrocarbons deposited on the outer surface of black powder by using Coats-Redfern at different heating rates including (10, 15, 20, and 25) Cº/min by using the flow rate 20 ml/min of helium as an inert gas, Activation energy increased 28.226-26.214 kJ/mole within the heating rate of 10-20 C^o/min, and entropy showed a decrease -281.749 to -279.66 J/Kmol, and enthalpy showed the same trend.

Abstract: In this paper, ‎morphological, physico-chemical and thermal properties investigations‎ are carried out for a ‎novel ‎composite material reinforced by Washingtonia Filifera (WF) palm fibers using a 20 weight (wt) % loading rate. The experimental analysis by Scanning Electron Microscopy (SEM) shows the longitudinal roughness of the surface, which plays a very important role in the adhesion between the WF fibers and the High Density ‎PolyethylenE (HDPE) resin. FTIR tests of the composite (WF 20%/ HDPE) represent out of plane vibrations involving ring and CH2 symmetric bending in cellulose chain.‎ Thermogravimetric analysis (TGA) and Derivative thermogravimetric ‎(DTG) thermal analysis show a thermal stability at 210°C, 2.5% residual mass ‎and 745 °C maximum ‎temperature. X-Ray Diffraction (XRD) analysis shows that the ‎crystallinity index is 59.2%, with a size of ‎‎23 nm. Using tensile tests, a Young modulus of 858.6 MPa, ‎17% elongation and a maximum stress of 15 MPa ‎are found. The obtained characteristics of WF reinforced composite are better than those of Bamboo reinforced composites which has been proven to have characteristics superior to those of standard particleboard and medium density fiberboard used mainly in the construction industry.

Abstract: Finite element model of dynamic tuned gyroscope (DTG) was founded using finite element software of ANSYS. Natural frequencies and vibration modalities of DTG in cases of both being static and rotating were studied respectively through the method of modal analysis, and also various vibration modalities influence on output of gyroscope was analyzed.

Abstract: The catalyst discarded from fluidized catalytic cracking (FCC) units of heavy oil fractions presents in its composition typically high concentrations of silica and alumina, which give to it the possibility to be used as a pozzolanic material. The pozzolanic activity of a spent FCC catalyst from a Brazilian refinery oil was evaluated by studying the influence of the substitution in different degrees of a type II cement, by this catalytic residue on the hydration process and on the compressive strength of the formed materials. The influence of different particle size fractions of the residue and of its milling process was studied as well. The pozzolanic activity was evaluated by thermogravimetry (TG), derivative thermogravimetry (DTG) and non-conventional differential-thermal analysis (NCDTA). The results show that the chemical pozzolanic activity is enhanced when the sample presents a higher specific surface, as well as, the milling of the residue it is fundamental in order to be accepted and used as a pozzolanic material on partial substitution to cement.

Abstract: In the process of production and processing of Dynamically Tuned Gyro, this paper analyzes the situation that the current accelerated stability test cannot be able to eliminate the residual stress fully which will causes drifting parameter varying of DTG based on FMMEA. The result shows that the residual stress is the important factor of DTG poor reliability. Here the new accelerated stability test profile was designed and verified in the test which eliminated the residual stress effectively. The research method and results has theoretical significance and practical value in making DTG reliability growth.

Abstract: This paper presents a new microelectromechanical hybrid gyroscope (MHG) with three equilibrium rings. This structure can eliminate the error caused by the double rotation frequency of the driving shaft successfully. The MHG kinematic equations with three equilibrium rings are derived in this paper. Meanwhile, a new digital design and simulation of the MHG closed-loop detection circuit are proposed based on FPGA. The noise interference is weakened by using differential mode signal detection and the resources of FPGA are decreased by the loop diode demodulation in this paper. The cross axis coupling of the decoupled system is about 2.4%. The phase margin is 70deg and the magnitude margin is 22db after correction. The transcient response simulation is tested when the inputs are sinusoidal functions. The bandwidth and scale factors of x-axis and y-axis closed loops are analyzed in the paper. The bandwidth can reach about 70Hz and the scale factors of x-axis and y-axis closed loops are 0.1467V/o/s and -0.1467V/o/s respectively.

Abstract: The difference between the attitude angle and the rotation angle will cause the modeling error of DTG. The accurate calculation model of azimuth is established according to the relationship between the attitude angle and rotation angle. The error between the accurate calculation model and the traditional model is analyzed by simulating. The simulation show that the modeling error is proportional to the tilt angle and the pitch angle, when the change of the tilt angle and the pitch angle is 1°, the max change of the modeling error will be 3.6701.

Abstract: The paper was to optimize the conditions of thermal and pressing dewatering of lignite based on four factors three levels of Orthogonal experiment and to study the effect of conditions on lignite burning characteristic. The results show that the importance to the dehydration rate of lignite is in turns, temperature, pressing time, pressure, particle size; and the optimizing condition is temperature 220°C, pressure 6MPa, pressing time 40min, and the particle size ratio 3 to 7. Thermo gravimetric analysis had been carried out to study the burning characteristic of the dewatered lignite. The results show that the burning characteristic temperatures: Preliminary release of volatile temperature, ignition point, point of maximum weightlessness rate, burnout temperature, are found to be an obvious rise, but the burnout temperature; and the four burning characteristic temperatures will be elevatory with the temperature elevated, pressing time extended and pressure increased.

Abstract: Tetragonal zirconia in alumina matrix is known as Zirconia Toughened Alumina (ZTA). ZTA ceramics are attractive materials due to the combination of both ZrO2 (high strength and fracture toughness) and Al2O3 (high hardness and wear resistance) properties. This work reports the synthesis of ultra-fine Al2O3–ZrO2 powders (20–200 nm) through the wet chemical route. Hundred percent tetragonal ZrO2 can be found in the sintered body Al2O3(matrix)-30%Y0.1Zr0.9O2 at 16000 C/2 h with 98% densification. The fine ZrO2 (100–300 nm) has been homogeneously dispersed within the alumina matrix with a maximum grain size of 0.8 μm, which will increase the toughness of the alumina matrix. High fracture toughness of Al2O3-30%Y0.1Zr0.9O2 is attributed to the presence of a coupled mechanism of stress-induced transformation toughening and transformation-induced microcrack toughening, and high flexural strength of the ceramics is a coupled result of small-size flaw and high fracture toughness. Because of no amorphous phases and grain boundaries but clean and stable phase interfaces in the ceramic composite, the Al2O3(matrix)-30%ZrO2 and Al2O3(matrix)-30%Y0.1Zr0.9O2 obtained in the experiment are promised to have excellent strength retention and high creep resistance at high temperature, compared to ones prepared by powder sintering method.