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71.
Nonlinear dynamic responses of a laminated hybrid composite plate subjected to time-dependent pulses are investigated. Dynamic equations of the plate are derived by the use of the virtual work principle. The geometric nonlinearity effects are taken into account with the von Kármán large deflection theory of thin plates. Approximate solutions for a clamped plate are assumed for the space domain. The single term approximation functions are selected by considering the nonlinear static deformation of plate obtained using the finite element method. The Galerkin Method is used to obtain the nonlinear differential equations in the time domain and a MATLAB software code is written to solve nonlinear coupled equations by using the Newmark Method. The results of approximate-numerical analysis are obtained and compared with the finite element results. Transient loading conditions considered include blast, sine, rectangular, and triangular pulses. A parametric study is conducted considering the effects of peak pressure, aspect ratio, fiber orientation and thicknesses. 相似文献
72.
Özlem Sarıöz Osman Serindaĝ Meysun İ. Abdullah 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1785-1795
Functionalized bis(amino)phosphines of the type PhP(NHR)2 ( 1a–c ) and aminophosphines of the type Ph2PNHR ( 2a–c ) have been synthesized by treating PhPCl2 or Ph2PCl with corresponding primary amines of H2N-R where R = -CH2SO3H, -C6H4SO3H, and benzo-15-crown-5. The molybdenum(0) complex of the aminophosphine ( 3 ) has been obtained by reacting cis-[Mo(CO)4(bipy)] with aminophosphine ( 2c ). The synthesized aminophosphines, bis(amino)phosphines, and the molybdenum(0) complex have been characterized by IR, 1H NMR, 31P NMR, and MS spectroscopic techniques and by elemental analysis. 相似文献
73.
Stark hole-burning spectroscopy is used to investigate the effective dipole moment change of cresylviolet perchlorate (CVP) in various glass and polymer hosts such as ethanol:methanol (EM), polyvinyl alcohol (PVA), poly (2-hydroxyethyl) methacrylate (PHEMA), polyvinylbutyral (PVB), and formamide. The strong correlation between effective dipole moment change of the guest molecule and the holeburning efficiencies of the host matrices illustrates the sensitivity of the dipole moment change as a direct measure of guest-host interactions. Hole-burning is found to be more efficient as the dipole induced reaction field increases. This relationship is discussed in terms of the unusual hole-burning mechanism suggested for this molecule. The effective dipole moment change of cresylviolet perchlorate ranges from 0.14 to 0.59 Debye. 相似文献
74.
Two distinct Josephson junctions (JJs) connected with a constant coupling resistance Rcp are theoretically considered to investigate the overall dynamics below and above the critical current Ic. The circuit model of the device is driven by two DC current sources, I1 and I2. Each junction is characterized by a nonlinear resistive–capacitive junction (NRCSJ). Having constructed the circuit model, time-dependent simulations are carried out for a variety of control parameter sets. Common techniques such as bifurcation diagrams, two-dimensional attractors and Lyapunov exponents are applied for the determination of chaotic as well as periodic dynamics of the superconducting junction devices. According to the findings, two states (namely superconducting and ordinary conducting) are determined as functions of the source currents. The chaotic current which flows through Rcp exhibits a very rich behavior depending on the source currents I1 and I2 and junction capacitances C1 and C2. The device characteristics are summarized by a number of three-dimensional phase diagrams in the parameter space. In addition, for certain parameters, hyper-chaotic cases with two positive Lyapunov exponents are encountered. In contrast to earlier studies claiming the need for a sinusoidal feeding current for generating a chaotic signal, our circuitry can easily generate one via a DC source. 相似文献
75.
The measurement of powder flowability is a major concern for most industrial processes that deal with the handling of bulk solids as raw materials,intermediates,or products.The development of devices that measure the flowability of non-aerated powders has not progressed as rapidly as might have been hoped since most research activities have been based on various types of shear testers intended to aid the design of hoppers.A new flowability indicator named as weighted cohesion (WS) is established using newly... 相似文献
76.
In this paper, we present a method for constructing multivariate tight framelet packets associated with an arbitrary dilation matrix using unitary extension principles.We also prove how to construct various tight frames for L2(Rd) by replac-ing some mother framelets. 相似文献
77.
Samet Solak Mehmet Karakuş 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):1054-1061
Abstract2,4-Bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (Lawesson’s reagent: LR) was reacted with 1,2:5,6-di-O-cyclohexylidene-α-D-glucofuranose and 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose in toluene and gave rise to crude dithiophosphonic acids. The crude dithiophosphonic acids were treated with excess triethylamine and the triethylammonium salts of dithiophosphonic acids (1) and (2) were isolated by crystallization method. Compounds 1 and 2 were characterized by elemental analysis, IR, and NMR (1H-, 13C- and 31P-) spectroscopies and mass spectrometry. In addition, NMR spectra, the electronic properties (the electronic chemical potential, electronegativity, chemical hardness and the global electrophilicity index) and NBO analysis of compound 2 have been calculated by using the Gaussian 16?W program. The electronic properties were calculated using Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energies by density functional method (DFT/B3LYP) at 6-31G(d,p) level. The HOMO and LUMO energies are ?5.9 and ?0.72?eV, respectively. The HOMO–LUMO energy difference is 5.18?eV and this value shows that compound 2 has a high stability and low reactivity. 相似文献
78.
Abstract 3-Tetrahydrofurfuryloxy-2-hydroxypropyl methacrylate monomer was prepared from methacrylic acid, tetrahydrofurfuryl alchol, and epichlorhydrin. Homopolymerization and copolymerization with (2-phenyl-1,3-dioxolane-4-yl)methyl methacrylate and N-vinyl pyrrolidone monomers were carried out in 1,4-dioxane solution at 60°C using benzoyl peroxide as initiator. Infrared, proton and carbon-13 nuclear magnetic resonance techniques were used in characterizations of the monomer, the homopolymer and the copolymers were determined by DSC technique. The copolymer compositions were estimated from 1H-NMR spectra. The reactivity ratios in copolymerization of 3-tetrahydrofurfuryloxy-2-hydroxypropyl methacrylate and (2-phenyl-1,3-dioxolane-4-yl) methyl methacrylate were calculated by both Kelen-Tüdos and Fineman-Ross methods. 相似文献
79.
HCl elimination in low ratio was first carried out from poly(vinyl chloride) to increase allylic chlorines. Partially dehydrochlorinated poly(vinyl chloride), having a macroinitiator effect, was grafted with tert‐butyl methacrylate via atom transfer radical polymerization in the presence of CuBr/2,2′‐bipyridine at 64°C in tetrahydrofuran. Original poly(vinyl chloride) was also grafted with tert‐butyl methacrylate under the same conditions to compare with that of partially dehydrochlorinated poly(vinyl chloride). The graft copolymers were characterized by elemental analysis, FTIR, 1H and 13C‐NMR, differential scanning calorimetry, and gel permeation chromatography (GPC). Thermal stabilities of the graft copolymers were investigated by thermogravimetric analysis as compared with those of the macroinitiators. 相似文献
80.
Electrically conductive composite systems based on polyvinyl chloride (PVC) and polymethyl methacrylate (PMMA) filled with metal powders of Al and Cu have been studied. The composite preparation conditions allow the formation of a random distribution of metallic particles in the polymer matrix. Dependence of the dielectric and conductivity properties of the PVC and PMMA/fillers was studied over a broad range of frequency and volume fraction of metal fillers. The experimental results could be explained by means of the conductivity of fillers and the interface polarization between polymers and fillers. Percolation was also seen in this study when the volume fraction of conducting fillers was close to critical value, in which the composites undergo an insulator‐conductor transition. The relation among the dielectric property and the fillers with different conductivity was proposed. 相似文献