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Dehghan Neda Payvandy Pedram Talebi Shahram 《Journal of Thermal Analysis and Calorimetry》2022,147(12):6615-6629
Journal of Thermal Analysis and Calorimetry - The knowledge of the thermal properties of textiles is important with regard to their vast applications in most industries. Thermal properties, as one... 相似文献
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Maryam Sa'at Masoud Yarmohammadi Mona Zamani Pedram Mansour Shahidzadeh Mohammad Sadegh Amini-Fazl 《国际化学动力学杂志》2019,51(5):337-345
A novel nanocomposite catalyst for thermal degradation of the ammonium perchlorate (AP) has been synthesized, and its effect on the thermal behavior of AP has been investigated. Preparation of the catalyst was carried out via functionalization of the graphene oxide with phenyl isocyanate and its noncovalent bonding to catocene. The catalytic activity of the catalyst was studied by thermal gravimetric analysis/differential scanning calorimetry at various heating rates. In addition, the effect of the catalyst on the AP thermal decomposition has been investigated by Kissinger and Friedman methods as two model-free methods for calculation of the activation energy parameter. According to the Kissinger method calculations, the Ea of AP decomposition reduced about 151 kJ⋅mol−1 lower than the reported value for pure AP in the presence of the catalyst. Calculation of the Ea value for various reaction conversion rates by the Friedman method also confirmed the Kissinger method results. 相似文献
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The influence of polymer characteristics on paper properties has not been well understood. In this work, we aimed at analyzing
the performance of various cationic-modified poly vinyl alcohols (CPVA), as dry strength additives, on the properties of high-yield
pulp (HYP). Various dosages of CPVA having different molecular weights (MW) and charge densities were applied on HYPs, and
the resulting paper properties were evaluated. Also, an atomic force microscope (AFM) was employed to evaluate the attraction/repulsion
force developed between modified fibers and AFM probes. Our results showed that the hydrophilicity and contact area of fibers
were increased via CPVA application. High MW CPVA with the charge density of 0.7 meq/g was the most effective one in improving
the properties of the fiber networks made from HYPs. The changes in the fiber morphology and chemistry played roles in improving
the properties of fiber networks. The introduction of similar charges on HYPs via applying various dosages of different CPVAs
confirmed that the changes in the fiber chemistry were not the only dominant factor in improving the properties. Additionally,
the significance of polymer bridging (polymer characteristics) on the network properties was hindered due to the presence
of fines in the HYP. 相似文献
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We present a method for analytically calculating the derivative couplings between a pair of configuration-interaction-singles (CIS) excited states obtained in an atom-centered basis. Our theory is exact and has been derived using two completely independent approaches: one inspired by the Hellmann-Feynman theorem and the other following from direct differentiation. (The former is new, while the latter is in the spirit of existing approaches in the literature.) Our expression for the derivative couplings incorporates all Pulay effects associated with the use of an atom-centered basis, and the computational cost is minimal, roughly comparable to that of a single CIS energy gradient. We have validated our method against CIS finite-difference results and have applied it to the lowest lying excited states of naphthalene; we find that naphthalene derivative couplings include Pulay contributions sufficient to have a qualitative effect. Going beyond standard problems in analytic gradient theory, we have also constructed a correction, based on perturbative electron-translation factors, for including electronic momentum and eliminating spurious components of the derivative couplings that break translational symmetry. This correction is general and can be applied to any level of electronic structure theory. 相似文献
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In the present paper, free vibration of a thin open curved shell with parabolic curvature was studied. This shell has a curvature with variable radius in one direction. The equations of motion of this shell were inferred by first order shell theory. According to perpendicular nature of loading on shell of marine structures, the assumptions of Donnell–Mushtari–Vlasov can be used with an acceptable level of accuracy and the in-plane displacement along shell straight direction “x” can be neglected as compared to the displacement in two other directions. The natural frequencies and mode shapes related to the first five vibrational modes were extracted using semi-analytical methods including power series method, Galerkin method and beam function method. The results of the semi-analytical methods were validated against those obtained by using the finite element method. Out of the studied semi-analytical methods, Galerkin method was found to have an appropriate convergence in both natural frequency and mode shape. Adopting eight terms of the response series, Galerkin method has an appropriate convergence compared with the results of finite element. 相似文献
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