direction. Figure 4 shows the relative values of E 0 /q and Q -1 for varnished wood plotted against the amount of lacquer applied. Again, the vibrationalproperties of the varnished specimens are normalized by those of ‘‘naked’’ specimens. Therefore, the results in Fig. 4 include the effects of veneer and adhesive as well as those of var- nishing. In both the unreinforced and veneer-reinforced wood, thicker varnishing resulted in lower E 0 /q and higher Q -1 values. As suggested by artisans, the varnish layer should be minimized to increase the amplitude of sound. Analysis using a multi-layered model
semiconductors which are characterized by a number of unique properties which make these materials promising for usage in different electronic devices, such as temperature detectors, deflectometers of laser beams, photoconducting cells, magnetic sensors, extenders and stabilizers of laser radiation, and photovoltaic applica- tions [1, 2]. Vibrationalproperties of ZnP 2 and CdP 2
Table 1 shows the oven-dry specifi c gravity and vibrationalproperties at 20°C and 65% RH. Because these values were obtained for a single block, they may not be repre- sentative values for muirapiranga; nevertheless, the specifi c gravity was comparable with pernambuco. The value of tan δ was a little higher than for pernambuco, but much lower than that for common Japanese hardwood (7 − 13 × 10 −3 ) reported by Sugiyama et al., 1
Abstract The radial trends of vibrationalproperties, repre- sented by the specifi c dynamic modulus (E′/ρ) and damping coeffi cient (tan δ), were investigated for three tropical rain- forest hardwood species (Simarouba amara, Carapa procera, and Symphonia globulifera) using free–free fl exural vibration tests. The microfi bril angle (MFA) was estimated using X-ray diffraction. Consistent patterns of radial variations were observed for all studied properties. E′/ ρ was found to decrease from pith to bark, which was strongly related to the increas- ing pith–bark trend of MFA. The variation of tan δ along the radius could be partly explained by MFA and partly by the gradient of extractives due to heartwood formation. The cou- pling effect of MFA and extractives could be separated through analysis of the log(tan δ ) versus log(E′/ ρ ) diagram. For the species studied, the extractive content putatively associated with heartwood formation generally tends to decrease the wood damping coeffi cient. However, this weak- ening effect of extractives was not observed for the inner part of the heartwood, suggesting that the mechanical action of extractives was reduced during their chemical ageing. Key words Tropical woods · Dynamic modulus · Damping coeffi cient · Microfi bril angle · Extractives
Abstract Wood plastic plywood (WPPW), composed of veneer and styrofoam, was manufactured without special adhesives such as urea–formaldehyde or phenol–formalde- hyde resins, and its vibrationalproperties were investigated. WPPW can be produced at 1 MPa and 160°C for 9 min (three-ply) and 12 min (five-ply). The dynamic Young’s modulus reached its highest value when the styrofoam thickness was 30 mm. The sound velocity and dynamic Young’s modulus had minimum values at a grain angle of 45°. The results for dynamic Young’s moduli measured by a longitudinal vibration method and an in-plane flexural vibration method were almost the same. Dynamic shear moduli were measured by an in-plane surface wave propa- gation test and an in-plane flexural vibration method. From the experimental results, the dynamic shear moduli at 0° and 90° by the two methods were relatively close, although the surface wave propagation test results were higher than those from the flexural vibration method. Dynamic shear moduli at a grain angle of 45° measured by the in-plane surface wave propagation test and calculated from theory were relatively close. The surface wave propagation test results were smaller than the results calculated from theory. The shear stress distribution factors were about 1.000–1.189 for WPPW.
temperature by t-test indicated that there was no significant difference as a whole, although there were significant differ- ences at some temperatures. Therefore, we concluded that there was no difference in the elastic and viscoelastic properties by temperature between the wetwood and the normal part under the changing temperature conditions. These results will be the basis to investigate the behavior of the wetwood during a drying process. We think that the wetwood shows the same mechanical behavior as the nor- mal part during the drying process.
advantages and disadvantages. The ab-initio results in har- monic approximation are the most accurate, and show ex- cellent agreement with experiment. Another advantage of that method is the possibility of calculating the eigenvec- tors, and thus studying in detail the vibrational modes and their relation with the atomic structure of CMA. However, the method disregards all anharmonic effects, and is lim- ited to unit cells of moderate size, so that any effects of disorder cannot be accounted for. The molecular dynamics method, on the other hand, requires classical interaction potentials, and therefore is less accurate a priori. Still, the qualitative agreement with experiment is very good, even if quantitatively the deviations from experiment are some- what larger than with the ab-initio methods. However, the potential we have used is a preliminary one, and likely can further be improved. The biggest advantage of the MD method is, that it can be used also with very large
In summary, DFT method have been used to investigates the electronic, structural, and vibrationalproperties of the effect of harmful gases on N-doped graphene at two different occupation sites (A and B). These gases included CO, CO 2 , OH, and B 2 . The result
As in the case of electromagnetic metamaterials, we can prepare some composites displaying an effective “ne- gative” elastic constant, analogous to the negative refrac- tive index [16,17]. In , the author is discussing the case of metamaterials, which are guest-host systems, having units possessing hidden resonant masses inside. Figures in Reference  are quite stimulating to study and discuss the vibrationalproperties of such structures. Among the many models composed of rigid cages with moving particles inside, let us use the simplest one we can imagine, that is a one-dimensional chain composed of rigid host-guest units.
the six corners of the Brillouin zone are called the Dirac points 3 . The peculiar electronic structure of graphene 5 implies that electrons have a negligible effective mass around the Κ point of the Brioullion zone (Dirac Point) and thus a high electrical conductivity. Besides their unusual electronic structure, vibrationalproperties and phonon spectra are also of fundamental interest from which many physical properties such as thermal conductivity and heat capacity can be derived. Furthermore phonons are crucial for studying the electrical transport properties. Electrons excited by optical methods can be scattered into another state by electron- phonon coupling (EPC). EPC is a key physical parameter for ballistic transport 6,7 , quantum Hall effect 8 , Raman spectra and phonon dispersions.
In recent years two particular methods, scanning probe microscopy and theoretical total energy calculations (based, particularly, on density functional theory), have led to major advances in our understanding of surface science. However, performed to the exclusion of more ‘traditional’ experimental methods that provide quantitative information on the composition, vibrationalproperties, adsorption and desorption energies, and on the electronic and geometrical structure, the interpretation of the results can be unnecessarily speculative. Combined with these methods, on the other hand, they give considerable added power to the long-learnt lesson of the need to use a range of complementary techniques to unravel the complexities of surface phenomena.
Abstract : This article proposes and designs the internal structure of the electrical cabinet which can achieve the 3-DOF (degrees-of-freedom) motion, and making it in the horizontal vibration environment with excitation frequency of 12.5Hz.Obtaining vibrationalproperties of its internal structure through the Simulink simulation results, which is to said that manipulator and low-voltage electrical appliances are not in the synchronous conditions. But it is necessary to make it in a state of near synchronization to ensure the accuracy of the reliability test of the variable load load with low-voltage electrical appliances. On this issue,to achieve the desired results through the PID feedback control to further optimize.
The chitosan constituents considered in this study are denoted as A for the monomer, AA for the dimer and AAA for the trimer glucosamine molecules. The structural parameters of the A, AA, and AAA have been obtained using electron density functional theory (DFT) with the Becke–Lee–Yang–Parr functional (B3LYP) and polarized split-valence basis set 6-31G(d, p). Firefly Quantum Chemical package, version 8.0.0  which is partially based on the GAMESS (US) source code  has been used. Firefly as a versatile computation package allowed us to determine the equilibrium structure, i.e. a structure that represents a minimum on a potential energy surface. With this calculation, the internal coordinates such as the internuclear distances, valence angles and the torsion angles, were obtained. This process was followed by a hessian calculation to calculate the vibrational spectra. In this step, the vibrational frequencies and IR intensities were computed.
and mechanical polarizability ‘d’ developed by  have theoretically calculated for EuSe and given in Table.1. By solving Eq.1 & 2 we can obtain the phonon spectra in the first Brillouin zone for the non-equivalent 48- allowed wave vectors. The frequency along with symmetry directions have been plotted against the wave vectors to obtain the phonon dispersion curves (PDCs) from both the models. These curves are compared with each other and with inelastic neutron scattering technique in Fig-1. The theoretical results obtained by three-body shell model. we have used the computed vibration spectra to study the dynamical properties like specific heat and IR/Raman spectra in the present paper. The specific heat and Debye temperature Θ D have been calculated as function of
Although direct construction of a unique structural model from FEM data is impos- sible, insight into the structural characteristics can be inferred from the other properties of the film. For example, the sputtered a-Si exhibits a density-deficit of ∼5% over c-Si as measured by RBS which can be attributed to the presence of nanopores. This is also indicated by the significant densification occurring under indentation testing. Moreover, the indentation hardness of as-sputtered a-Si is slightly increased over as-implanted a-Si which may be due to the defects present in the as-implanted case facilitating deforma- tion via plastic flow more easily. The presence of this microstructure is not surprising as sputter-deposition is well known to result in gas inclusions and microstructural features such as columnar growth and porosity . Therefore, the nature of the inhomogeneities giving rise to the high degree of MRO in the present work is tentatively attributed to such void-like and microstructural features that are a result of a low density. In support of this,