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This paper presents the procedure of uniaxial mechanical characterization of composite solid rocket propellant based on hydroxy-terminated polybutadiene (HTPB), whose mechanical properties strongly depend on temperature, strain rate, natural aging and accumulated damage. A method of processing data is presented in order to determine time-temperature shift factor and master curves for tensile strength, ultimate strain and relaxation modulus, depending on reduced time. Functional dependences of these features represent an input for structural analysis of a rocket motor propellant grain. The effects of natural aging on the mechanical properties are also considered. [Projekat Ministarstva nauke Republike Srbije, br. TR 36050: Research and development of unmanned aircraft in support of traffic infrastructure monitoring]

Just in time (JIT) production is a new approach and way of thinking in the management of industrial organizations, the principles and methods of which seek the complete and comprehensive elimination of wastage and the enhancement of productivity in all activities inside and outside the organization .Accordingly, the purpose of the present research is the comparative evaluation of the components of just in time production within the various industrial groups of Tabriz. The statistical population of the research includes 576 factories in the four industries-machinery and equipment , chemical substances and products , textiles , and electronics and the related equipment-in small and medium scales in Tabriz . The sample size has been 313 based on the relation in limited populations and through the use of relative stratified sampling method . The researchers have used a questionnaire in order to collect data , and the data have been analyzed by multivariate ANOVA. The results indicate that there is a difference amony the four industries regarding lean production components .

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The effects of temperature and slice thickness on the drying kinetics of turmeric (Curcuma longa) slices are modeled to obtain a generalized master curve equation. Drying data obtained from experiments carried out in a laboratory scale tray dryer at different drying temperatures in the range of 40-70°C for different turmeric slice thicknesses (3-10 mm), are fitted to Midilli- Kucuk model (R² > 0.992), the best fitted model among the common semi-theoretical models. To incorporate the temperature and slice thickness effects, temperature-thickness superposition technique was applied in two stages. In the first stage, at a given drying temperatures moisture ratio is expressed as a function of 'reduced time' (t.ah) which is the product of drying time (t) and a thickness shifting factor (ah). Thickness reduced master curves obtained at each temperature are again shifted by temperature shift factor (aT) to generate a single master curve expressing moisture ratio as a function of another reduced time, t", product of drying time (t), thickness shifting factor (ah), and temperature shift factor (aT), to obtain the generalized Midilli-Kucuk model (MR(t.ah.aT,)). Temperature dependence of ah could be regressed into the Arrhenius - type equation, and aT could be regressed into a linear equation. The developed model was compared to the generalized drying model based on generalized drying rate constant, where upon both the models were found to yield prediction of turmeric slice drying with high accuracy (R² value > 0.99). [ABSTRACT FROM AUTHOR]

According to an influential dual-process model, a moral judgment is the outcome of a rapid, affect-laden process and a slower, deliberative process. If these outputs conflict, decision time is increased in order to resolve the conflict. Violations of deontological principles proscribing the use of personal force to inflict intentional harm are presumed to elicit negative affect which biases judgments early in the decision-making process. This model was tested in three experiments. Moral dilemmas were classified using (a) decision time and consensus as measures of system conflict and (b) the aforementioned deontological criteria. In Experiment 1, decision time was either unlimited or reduced. The dilemmas asked whether it was appropriate to take a morally questionable action to produce a greater good outcome. Limiting decision time reduced the proportion of utilitarian (yes) decisions, but contrary to the model’s predictions, (a) vignettes that involved more deontological violations logged faster decision times, and (b) violation of deontological principles was not predictive of decisional conflict profiles. Experiment 2 ruled out the possibility that time pressure simply makes people more like to say no. Participants made a first decision under time constraints and a second decision under no time constraints. One group was asked whether it was appropriate to take the morally questionable action while a second group was asked whether it was appropriate to refuse to take the action. The results replicated that of Experiment 1 regardless of whether yes or no constituted a utilitarian decision. In Experiment 3, participants rated the pleasantness of positive visual stimuli prior to making a decision. Contrary to the model’s predictions, the number of deontological decisions increased in the positive affect rating group compared to a group that engaged in a cognitive task or a control group that engaged in neither task. These results are consistent with the view

In this paper, the relaxation modulus of a single spun yarn is modeled in terms of the relaxation modulus of the constituent fibers of the yarn. A generalized Maxwell model is employed to describe the viscoelastic characteristic function of individual fibers subject to a given step function of tensile strain. The thermal history is considered by a temperature-related reduced time by assuming a thermo-rheologically simple material. The physical ageing process of textile fibers is considered by introducing an ageing related reduced time for glassy semi-crystalline polymer fibers. The effect of humidity is ignored. The model is extended to consider relaxation moduli of fibers undergoing different initial strain levels. With this general relaxation model of fiber, the response of the yarn to a step function of the yarn tensile strain is calculated using a force analysis method and a discrete fiber modeling approach. Experimental validation shows that the prediction agrees reasonably well with the experimental data. [ABSTRACT FROM AUTHOR]

Glass has useful optical properties but shows unfavorable mechanical performance such as poor impact resistance. As a way to improve such inferior mechanical performance, glass undergoes tempering processes which introduce through-thickness residual stress. Here, the residual stress is numerically analyzed for a soda-lime silicate glass plate under the one-dimensional through-thickness symmetric boundary conditions. As for the constitutive law, the structural relaxation model was used to account for the non-equilibrium thermodynamic state of micro-structures in calculating volume change during cooling and also the visco-elastic nature of mechanical properties. Results obtained using improved numerical methods were compared with experiments as well as results available in previous literatures. [ABSTRACT FROM AUTHOR]

In this article, the results of an investigation on solid propellant grains considering the effect of Poisson's ratio v under thermal loading are presented. Traditionally the v value of solid propellant grains is assumed to be a constant (e.g. 0.4999) for engineer, but the real v value is dependent on the real chemical recipe design of solid propellant grains. In order to simulate the time-temperature-dependent behaviour of thermoviscoelastic propellants under various Poisson's ratios, concepts of the time-temperature shift principle and reduced integration were used for finite element simulation. Results show that the effect of Poisson's ratio is important for structural integrity of solid propellant grains because the type of polymer material is changed from incompressible (vν &asim; 0.5) to compressible (vν ≠ 0.5). Under thermal loading, the difference between the maximum principal thermal strains for vν = 0.4999 and vν = 0.470 is 68.8 per cent, that between the maximum principal thermal stresses for vν = 0.4999 and vν = 0.470 is 73.5 per cent and that between the maximum shear thermal stresses for vν = 0.4999 and vν = 0.470 is 74.8 per cent. In addition, there are differences in the quasi-elastic analysis because the effect of Poisson's ratio becomes more and more predominant as the material type of solid propellant grains changed from incompressible to compressible. [ABSTRACT FROM AUTHOR]

For structural integrity evaluation of solid propellant grains, an accurate estimation of the stress and strain response is essential, because of the viscoelastic nature of the polymer material. The results of an investigation on solid propellant grains considering the effect of Poisson''s ratio υ variation under ignition pressurization are presented. Traditionally the υ value of solid propellant grains is assumed to be a constant (e.g. 0.4999) to simplify the experimental task, but the real υ value is from 0.47 to 0.4999 depending on the chemical design of the solid propellant grains. In order to simulate the time–temperature-dependent behaviour of viscoelastic polymer materials for a range of Poisson''s ratio values, the concepts of a time–temperature shift principle and reduced integration were used. In addition, eight different Poisson''s ratio values from 0.47 to 0.4999 were assumed and compared using the finite element method. Results show that the Poisson''s ratio variation effect is very important for structural integrity of solid propellant grains, and the stress and strain responses versus Poisson''s ratio variation are nonlinear because the type of polymer material is changed from incompressible to compressible. Under ignition pressure loading, the stress and strain responses in the compressible case (υ≠0.5) are much higher than those of the incompressible case (υ≒0.5). Therefore unlike metallic structures, an exact value of Poisson''s ratio for polymer materials is very important, and an improper assumption (υ≒0.5) may cause the structural integrity of a missile system subjected to pressure loading to be wrongly evaluated. [Copyright &y& Elsevier]

Traditionally, the nonlinear thermoviscoelastic analysis of solid propellant grains subjected temperature loading was not considered, and quasi-elastic analysis was widely adopted for structural integrity because of simplifying the analytical task. But it does not mean that the nonlinear effect is not useful and could be neglected arbitrarily, and this effect usually plays a very important role for some critical design. In order to simulate the material and geometrical nonlinearities, a step-by-step finite element model accompanied by concepts of time–temperature shift principle, reduced integration and thermorheologically simple material assumption was used. Results show that the material nonlinear effect is important for structural integrity of solid propellant grains under higher temperature surrounding, the effect of nonlinearity is not obvious under lower temperature surrounding, and the differences between linear and nonlinear analysis results become more and more predominant as temperature increases. In addition, the maximum shear stress obtained from the nonlinear simulation considering bulk modulus variation with compressive stresses are higher than those from linear simulation, and the effect of material nonlinearity is more predominant as compared to the effect of geometrical nonlinearity. From the work of linear and nonlinear analyses, the nonlinear thermoviscoelastic analysis highlighted several areas of interest and a more accurate and reasonable result could be obtained for engineer. [Copyright &y& Elsevier]

A constitutive equation with a dilatation dependent reduced time is used to model the mechanical response of solid amorphous polymers such as polycarbonate. Such constitutive equations have the property that stress relaxation occurs faster with increasing dilatation. In previous work, it has been shown that this constitutive equation can account for yield in materials undergoing uniaxial strain or stress control histories. In the present work, yield is discussed when materials described by this constitutive equation undergo homogeneous biaxial and triaxial strain histories. Four sets of conditions are considered: in-plane biaxial constant strain rate histories and in-plane biaxial constant stress rate histories, for both plane stress and plane strain states. Yield is defined in a manner analogous to that in the corresponding strain and stress control conditions in the uniaxial case. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a novel method for establishing an efficiency map of interior permanent-magnet synchronous motors that are used for electric vehicle propulsion, by employing the finite-element method (FEM) and a neural network (NN) to reduce the analysis time. The electro-magnetic analysis of motors using the FEM, particularly iron loss analysis, is significantly time-consuming owing to the nonlinearity and the post-processing. Moreover, to obtain an efficiency map, a data map of the d-q flux linkages based on the d-q currents should be established. At this stage, we compute the flux densities in all the elements, and they are learned by the NN to obtain a function of the d-q currents. Subsequently, the iron losses at all operating points are calculated using the learned data via the harmonic loss method. The results of the proposed method indicate that the time required to obtain the efficiency map is reduced; furthermore, the results are validated via a comparison with the FEM results. [ABSTRACT FROM AUTHOR]

Rapid and accurate diagnosis of meningitis/encephalitis (M/E) is essential for successful patient outcomes. The FilmArray® meningitis/encephalitis Panel (MEP) is a multiplexed PCR test for simultaneous, rapid detection of pathogens directly from cerebrospinal fluid (CSF) samples. 94 prospectively collected CSF specimens from patients with clinical suspicion of infective M/E underwent testing for 14 pathogens simultaneously, including Escherichia coli , Haemophilus influenzae , Neisseria meningitidis , and Varicella zoster . MEP demonstrated 95% agreement with current PCR methods, resulting in 16 diagnosed cases of M/E. Typically, the FilmArray® MEP results were delivered within approximately one hour, contrasting with current practices taking up to 5.6 days. Given the significant morbidity and mortality associated with delayed diagnosis of central nervous system infections, the FilmArray® MEP is a useful addition to the diagnostic capabilities of a clinical microbiology department., (© 2020 The Authors.)

To reduce the DNA profiling time, DNA samples were amplified using AmpFℓSTR ® Identifiler ® kit at reduced PCR cycling time amplification method without addition of any enhancement buffers or enzymes. The results showed no significant difference in the quality of the profiles produced compared to those produced in the manufacturer recommended condition. This study contributed in saving almost 25% of the time needed for PCR amplification without compromising the quality of the profiles. [ABSTRACT FROM AUTHOR]