The Cauchy Problem for a One Dimensional Nonlinear Peridynamic Model

This paper studies the Cauchy problem for a one-dimensional nonlinear peridynamic model describing the dynamic response of an infinitely long elastic bar. The issues of local well-posedness and smoothness of the solutions are discussed. The existence of a global solution is proved first in the sublinear case and then for nonlinearities of degree at most three. The conditions for finite-time blow-up of solutions are established.Comment: To appear in Journal of Differential Equations (added references, corrected typos, minor revision in Section 2, 18 pages

Modulational instability of two pairs of counter-propagating waves and energy exchange in two-component media

The dynamics of two pairs of counter-propagating waves in two-component media is considered within the framework of two generally nonintegrable coupled Sine-Gordon equations. We consider the dynamics of weakly nonlinear wave packets, and using an asymptotic multiple-scales expansion we obtain a suite of evolution equations to describe energy exchange between the two components of the system. Depending on the wave packet length-scale vis-a-vis the wave amplitude scale, these evolution equations are either four non-dispersive and nonlinearly coupled envelope equations, or four non-locally coupled nonlinear Schroedinger equations. We also consider a set of fully coupled nonlinear Schroedinger equations, even though this system contains small dispersive terms which are strictly beyond the leading order of the asymptotic multiple-scales expansion method. Using both the theoretical predictions following from these asymptotic models and numerical simulations of the original unapproximated equations, we investigate the stability of plane-wave solutions, and show that they may be modulationally unstable. These instabilities can then lead to the formation of localized structures, and to a modification of the energy exchange between the components. When the system is close to being integrable, the time-evolution is distinguished by a remarkable almost periodic sequence of energy exchange scenarios, with spatial patterns alternating between approximately uniform wavetrains and localized structures.Comment: 35 pages, 13 figure

Strong state vs. Weak society

This paper argues that the distribution of material capabilities in state society relations is the main factor shaping the regime of Middle Eastern states. This premise suggests that sustainable democracy in the Arab world fails to flourish because states with their centralized bureaucracies are too powerful compared to the large portions of the societies. Even with the somewhat limited power and influence of the most affluent members of civil society, there are no real autonomous actors in the Middle Eastern beyond the central state. Civil Society is too weak to check the state’s continuing power. This is the most fundamental cause for the lack of democratization in the Middle East. States are too strong societies are too weak

Favouritism in Ship Management: A Scale Development and Validation

The most important determinant of quality and safety in ship management is human resources. Personnel turnover rate, job satisfaction level of seafarers, organizational commitment, high level and individual well-being of the employees, have an important role in ensuring quality and safety. In many studies, it may be seen in the results of research that favouritism increases job stress and personnel turnover rate, while decreasing job satisfaction, organizational commitment, motivation, and teamwork. Favouritism has a negative impact on safety and quality management of ships. Based on this important consideration, in this study seafarers\u27 perceptions have been measured, with an aim at developing a valid and reliable favouritism scale. The scale questions, prepared on the basis of semi-structured interviews and favouritism studies, have been applied to 252 different seafarers. As a result of the factor analyses conducted in SPSS 23, a 22-item favouritism scale, consisting of three factors related to demographic and personal characteristics, social rights and opportunities and operational processes, has been developed. The reliability and validity studies of the scale have been conducted, and it has been observed that the scale has high reliability

The effect of cutting direction and water based varnish type on sound absorption coefficient in some native wood species

Noise which could be defined as disturbing sound, is becoming a major problem depending with developing technology. Controlling the noise helps raising the quality of life to higher levels. Although the intensity of the noise is not at a level that will affect human health, it should be reduced or eliminated, for better life standart. Due to the adverse effects of the noise level on health; the acoustic properties of living areas require serious consideration. Sound absorption coefficients of the materials used in the interior play an important role in providing sensory comfort depending on the volume. Natural and artificial wood are commonly used materials in interior design, especially in the construction of partition elements. In addition, wood is natural material and it has some important advantages and disadvantages. In this study the sound absorption coefficients of eastern beech and scotch pine trees, which are the most preferred materials in interior design, were investigated. For this pupose, these wood materials were cut superficially and radially according to the intersection directions, then the sample surfaces were varnished with one and two component water-based varnishes that do not contain solvent-based resin. The sound absorption coefficients of the obtained samples were determined by the impedance tube method and the results were compared statistically. It has been investigated that the obtained results could be evaluated statistically within the frequency values, besides, different results could be obtained according to the characteristics of natural wood materials, the direction of intersection and water-based varnish types. According to the findings obtained as a result of the study, it has been suggested that if natural wood material is used indoors, the superficial cross-section of East beech wood should be used according to the direction of intersection, and a two-component varnish should be used according to the varnish type