•4-Aminoantipyrine (4-AAP) was grown using solvent assisted followed by the solvent slow evaporation method under ambient conditions.•Structural, optical, NLO and thermo-mechanical studies, and their ...significant results are discussed in detail.•The electrical conductivity and dielectric behavior of the 4-AAP crystal change with respect to the increasing applied frequency were discussed in detail.•The optimized geometry structure, vibrational bands, optical band, molecular electrostatic potential, and Mulliken atomic charge population of the 4-AAP were examined through DFT techniques.
The aim of this work was to grow organic single crystals of 4-Aminoantipyrine (4-AAP) under ambient conditions, using a solvent slow evaporation method, and then to investigate the crystal structure, optical band gap, optical transmittance behavior, second harmonic generation efficiency, thermal stability, material rigidity, and dielectric responses for opto-electrical based device applications. The powder X-ray diffraction (XRD) and single crystal XRD analyzes revealed the hexagonal crystal structure and lattice parameter values of the as-grown 4-AAP. The respective molecular vibration bands and functional groups of the as-grown 4-AAP were identified using the experimental and theoretical FT-IR analysis. The optical absorption and transmittance spectrum of the 4-AAP single crystals revealed good transparency throughout the visible region. The non-linear optical (NLO) characteristics of the 4-AAP crystals were tested using the Kurtz and Perry powder technique. Thermal gravimetric (TGA) and differential thermal analysis (DTA) were used on the as-grown crystals, to determine their weight loss and heat absorption/release process. The hardness vs load plot can be used to determine the hardness values and response of the hard as-grown 4AAP crystals under the influence of load. The electrical conductivity and dielectric behavior of the 4-AAP crystals changed as the applied frequency increased. Computational techniques were used to investigate the 4-AAP's optimized geometrical structure, theoretical optical band, molecular electrostatic potential, and Mulliken atomic charge population.
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The composite post insulator composed of a large diameter mandrel and flange pressed by a one-time integral pultrusion has high strength and good toughness and is widely used in the existing flexible ...converter valve. For constructing the finite element model of the crimped post insulator, most of the flange surface and the mandrel surface are directly connected, making the simulation model’s stiffness deviate from the actual model and the model distortion. Based on this, this study proposes a new finite element simplified model of crimped composite post insulator based on multi-point constraints (MPC), which accurately simulates the crimping area of mandrel and flange in engineering practice. It verifies the model’s reliability through static tests and characteristic vibration tests. The results show that the difference between the finite element simulation and the test results is within 5%. The finite element modeling method based on MPC local constraints is very reliable in applying crimped composite post insulators. Based on the proposed model, the influence of flange height and thickness on the mechanical properties of composite post insulators is further explored. The results show that the influence of flange height on mechanical properties can be ignored when the height of the insulator stiffener (non-press common area) is constant. Within the allowable thickness range of the flange crimping process, the increase in flange thickness will significantly reduce the maximum bending stress of the insulator and increase its safety margin. It provides a good design idea for the design of crimping composite insulators.
Biaxial strength testing of brittle materials is claimed to have some benefits compared to uniaxial testing, e.g. the much simpler specimen preparation, the avoiding of tensile loaded edges, the ...similarity of the stress state to those from typical loading (e.g. during a thermal shock loading) and the fact, that biaxial stress states are more revealing of defects than uniaxial stress states. The experience of the past showed, that biaxial strength testing has its own problems, to avoid these led to the development of several variants. One of these variants, the ball on three balls test, seems to be extremely simple: a disc is supported by three balls and then axially loaded from the opposite side via a fourth ball. In this system small deviations from the requested geometry, especially some out of flatness of the disc, are mentioned to be tolerable, but the threefold bending symmetry makes an exact analytical assessment of the stress state in the loaded disc extremely difficult. A numerical approach has yet not been performed. In this paper a FE analysis of the stress state in a ball on three balls tested disc is performed. The stress field scales with the maximum principle stress, which occurs in the centre of the tensile surface. For this stress an analytical approximation (which has been fitted to the numerical results) is given, which accounts for the influence of all relevant geometrical and material parameters. The investigated range of parameters considers the values typical for testing of brittle materials.
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Friction stir welding (FSW) is considered to be the most significant development in metal joining in decades and, in addition, is a "green" technology due to its energy efficiency, environmental ...friendliness, and versatility. This process offers a number of advantages over conventional joining processes. Furthermore, because welding occurs via the deformation of material at temperatures below the melting temperature, many problems commonly associated with joining of dissimilar alloys can be avoided, and thus, high-quality welds are produced. Due to this fact, FSW has been widely used in different industrial applications where metallurgical characteristics should be retained, such as in the aeronautic, naval, and automotive industries. The computational modeling of FSW processes is an extremely challenging task due to the highly nonlinear and coupled nature of the physical problem and the numerical issues that need to be properly addressed. This is why the numerical simulation of FSW processes has been a very active research field in the last few decades. Despite the complexity of the physical problem and its numerical simulation, significant advances in the field have been achieved as a result of interdisciplinary research on related fields of computational mechanics, constitutive modeling, materials characterization, mathematical analysis, and numerical methods. This book collects some of the last developments in the fields of FSW, friction stir spot welding, and friction stir processing, written by well-known researchers who have contributed significantly to advances in the computational modeling, numerical simulation, and material characterization of those processes.
Power transformers are key components in electric power distribution and transmission systems, and it is essential that they function properly for many years. With increasing age, there are potential ...risks of extremely high monetary losses due to unexpected failures and outages. A simple solution would be to replace all aging and risky transformers at once with new ones. Such an approach is obviously not a fiscally realistic solution. The main objectives are to extend their service life and optimize their performance through increased availability. For these reasons, in the past decades transformer life management has gained an ever-increasing interest. The greatest challenges are related to the need for methods to assess their condition and life expectancy along with the improvement of transformers’ efficiency by noble designs and/or the application of new materials. This book covers some theoretical and practical developments with special emphasis on R&D trends in transformer diagnostics and monitoring. Graduate-level students and academics as well as scientists and engineers involved in power equipment design, diagnostics, and monitoring will benefit from this book.
In the industrial manufacturing of metals, the achievement of products featuring desired characteristics always requires the control of process parameters in order to obtain a suitable ...microstructure. The strict relationship among process parameters, microstructure, and mechanical properties is a matter of interest in different areas, such as foundry, plastic forming, sintering, welding, etc., and regards both well-established and innovative processes.
Nowadays, circular economy and sustainable technological development are dominant paradigms and impose an optimized use of resources, a lower energetic impact of industrial processes and new tasks for materials and products. In this frame, this Special Issue covers a broad range of research works and contains research and review papers.
The quantitative effects of a new gum, used as a binder, on the mechanical and release properties of paracetamol tablet formulations were analyzed in a 23 full factorial experiment. Cissus gum ...extracted from Cissus populnea Guill. & Perr. (Vitaceae) was compared with official gelatin. The individual and interaction effects of type of binder, concentration of binder and packing fraction on the friability, tensile strength, brittle fracture index, disintegration time and drug release profile of tablets were determined. Changing the binder from gelatin to cissus gum led to an increase in friability and a decrease in tensile strength, brittle fracture index (BFI) and drug release variables. Increasing binder concentration from 2.0w/w to 4.0%w/w, and increasing relative density from 0.80 to 0.90, led to increases in lamination tendency and release rate of the formulations. Tablets containing gelatin had higher tensile strength, lower friability, longer disintegration time and a greater tendency to laminate than those with cissus gum. Hence, care must be taken in choosing a suitable binder for tablet formulations, with respect to their mechanical and release characteristics. The study suggests that cissus gum should be preferred to gelatin in tablet formulations that tend to cap or laminate or in formulations meant for rapid drug release.
Copoly(ester-sulfonates) of varying compositions have been synthesized by interfacial polycondensation technique by using H
2O–CHCl
3 as an interphase, alkali as an acid acceptor and sodium lauryl ...sulfate-cetyl trimethyl ammonium bromide as mixed emulsifiers at 0 °C for 4
1
2
h. Copolymers are characterized by IR and NMR spectral data, viscosity in three different solvents at three temperatures and little solvent and temperature effect is found on
η; and density (1.3430–1.3406 g/cm
3) by floatation method. Copolymers possess excellent solubility in common solvents and chemical resistance against water, acids, alkalis and salts. They possess moderate to good tensile strength (10.6–79.5 N/mm
2), excellent volume resistivity (7.5–28
×
10
16 Ω
cm), electric strength (53–118 kV/mm) and dielectric constant (1.3–1.58). They are thermally stable up to about 349–373 °C in an N
2 atmosphere and possess high
T
g (136–196 °C). DTA endo/exothermic transitions supported either decomposition or formation of new product(s). Physical properties of copolymers are improved with increasing terephthlate content.
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